Aircraft having thrust to weight dependent transitions

ABSTRACT

An aircraft includes an airframe having first and second wings with first and second pylons extending therebetween and having a two-dimensional distributed thrust array of outboard propulsion assemblies attached thereto. A flight control system is coupled to the airframe and is operable to independently control a rotor speed and a thrust vector of each propulsion assembly. In a low thrust to weight configuration, transitions from the VTOL orientation to the biplane orientation include establishing a pitch down flight attitude while engaging in collective thrust vectoring of the outboard propulsion assemblies to maintain hover stability followed collectively reducing the thrust vector angles to initiate forward flight. In a high thrust to weight configuration, transitions from the VTOL orientation to the biplane orientation include maintaining a level flight attitude while collectively increasing the thrust vector angles of the outboard propulsion assemblies to initiate forward flight.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of co-pendingapplication Ser. No. 15/972,431 filed May 7, 2018, which is acontinuation-in-part of application Ser. No. 15/606,242 filed May 26,2017, which is a continuation-in-part of application Ser. No. 15/200,163filed Jul. 1, 2016, now U.S. Pat. No. 9,963,228, the entire contents ofeach is hereby incorporated by reference.

TECHNICAL FIELD OF THE DISCLOSURE

The present disclosure relates, in general, to aircraft operable totransition between thrust-borne lift in a VTOL orientation andwing-borne lift in a biplane orientation and, in particular, to aircrafthaving multiple VTOL to biplane transition procedures selected basedupon the thrust to weight configuration of the aircraft.

BACKGROUND

Fixed-wing aircraft, such as airplanes, are capable of flight usingwings that generate lift responsive to the forward airspeed of theaircraft, which is generated by thrust from one or more jet engines orpropellers. The wings generally have an airfoil cross section thatdeflects air downward as the aircraft moves forward, generating the liftforce to support the airplane in flight. Fixed-wing aircraft, however,typically require a runway that is hundreds or thousands of feet longfor takeoff and landing. Unlike fixed-wing aircraft, vertical takeoffand landing (VTOL) aircraft do not require runways. Instead, VTOLaircraft are capable of taking off, hovering and landing vertically. Oneexample of VTOL aircraft is a helicopter which is a rotorcraft havingone or more rotors that provide lift and thrust to the aircraft. Therotors not only enable hovering and vertical takeoff and landing, butalso enable, forward, backward and lateral flight. These attributes makehelicopters highly versatile for use in congested, isolated or remoteareas where fixed-wing aircraft may be unable to takeoff and land.Helicopters, however, typically lack the forward airspeed of fixed-wingaircraft.

A tiltrotor aircraft is another example of a VTOL aircraft. Tiltrotoraircraft generate lift and propulsion using proprotors that aretypically coupled to nacelles mounted near the ends of a fixed wing. Thenacelles rotate relative to the fixed wing such that the proprotors havea generally horizontal plane of rotation for vertical takeoff, hoveringand landing and a generally vertical plane of rotation for forwardflight, wherein the fixed wing provides lift and the proprotors provideforward thrust. In this manner, tiltrotor aircraft combine the verticallift capability of a helicopter with the speed and range of fixed-wingaircraft. Tiltrotor aircraft, however, typically suffer from downwashinefficiencies during vertical takeoff and landing due to interferencecaused by the fixed wing. A further example of a VTOL aircraft is atiltwing aircraft that features a rotatable wing that is generallyhorizontal for forward flight and rotates to a generally verticalorientation for vertical takeoff and landing. Propellers are coupled tothe rotating wing to provide the required vertical thrust for takeoffand landing and the required forward thrust to generate lift from thewing during forward flight. The tiltwing design enables the slipstreamfrom the propellers to strike the wing on its smallest dimension, thusimproving vertical thrust efficiency as compared to tiltrotor aircraft.Tiltwing aircraft, however, are more difficult to control during hoveras the vertically tilted wing provides a large surface area forcrosswinds typically requiring tiltwing aircraft to have either cyclicrotor control or an additional thrust station to generate a moment.

SUMMARY

In a first aspect, the present disclosure is directed to an aircraftoperable to transition between thrust-borne lift in a VTOL orientationand wing-borne lift in a biplane orientation. The aircraft includes anairframe having first and second wings with first and second pylonsextending therebetween. The first and second wings each have first andsecond outboard nacelle stations. A two-dimensional distributed thrustarray is attached to the airframe. The thrust array includes a pluralityof outboard propulsion assemblies coupled to the first and secondoutboard nacelle stations of the first and second wings. The thrustarray is operable to provide thrust for the aircraft. A flight controlsystem is coupled to the airframe and is operable to independentlycontrol a rotor speed and a thrust vector of each of the propulsionassemblies. In a low thrust to weight configuration of the aircraft,transitions from the VTOL orientation to the biplane orientation includeestablishing a pitch down flight attitude while engaging in collectivethrust vectoring of the outboard propulsion assemblies to maintain hoverstability followed by collectively reducing the thrust vector angles toinitiate forward flight. In a high thrust to weight configuration of theaircraft, transitions from the VTOL orientation to the biplaneorientation include maintaining a level flight attitude whilecollectively increasing the thrust vector angles of the outboardpropulsion assemblies to initiate forward flight.

In certain embodiments, the outboard propulsion assemblies may beunidirectional thrust vectoring propulsion assemblies. In otherembodiments, the outboard propulsion assemblies may be omnidirectionalthrust vectoring propulsion assemblies. In some embodiments, in the lowthrust to weight configuration, the aircraft may have a thrust to weightratio below a predetermined threshold such as a thrust to weight ratiobelow 1.4. In certain embodiments, in the low thrust to weightconfiguration, the aircraft may have a thrust to weight ratio betweenabout 1.1 and about 1.4. In some embodiments, in the high thrust toweight configuration, the aircraft may have a thrust to weight ratioabove a predetermined threshold such as a thrust to weight ratio above1.7. In certain embodiments, the first and second wings may each havefirst and second inboard nacelle stations having inboard propulsionassemblies coupled thereto. In such embodiments, the outboard propulsionassemblies may be omnidirectional thrust vectoring propulsion assembliesand the inboard propulsion assemblies may be non thrust vectoringpropulsion assemblies. Alternatively, the outboard propulsion assembliesmay be longitudinal thrust vectoring propulsion assemblies and theinboard propulsion assemblies may be lateral thrust vectoring propulsionassemblies. In some embodiments, the first and second pylons may eachinclude an inboard nacelle station having an inboard propulsion assemblycoupled thereto. In such embodiments, the outboard propulsion assembliesmay be omnidirectional thrust vectoring propulsion assemblies and theinboard propulsion assemblies may be non thrust vectoring propulsionassemblies.

In certain embodiments, the pitch down flight attitude while engaging incollective thrust vectoring of the outboard propulsion assemblies tomaintain hover stability, may be a pitch down flight attitude of betweenabout 10 degrees and about 20 degrees or a pitch down flight attitude ofbetween about 20 degrees and about 30 degrees. In some embodiments,transitions in the low thrust to weight configuration may includecollectively reducing in the thrust vector angles and increasing thepitch down attitude until the thrust vectors are substantiallyhorizontal and the wings are substantially horizontal. In certainembodiments, transitions in the high thrust to weight configuration mayinclude maintaining the thrust vector angles and increasing the pitchdown attitude until the thrust vectors are substantially horizontaland/or collectively reducing thrust vector angles and increasing thepitch down attitude while maintaining the thrust vectors substantiallyhorizontal until the wings are substantially horizontal. In someembodiments, each of the outboard propulsion assemblies may include anaerosurface. In such embodiments, transitions in the low thrust toweight configuration may include collectively tilting the aerosurfacesto create a pitch down moment on the aircraft.

In a second aspect, the present disclosure is directed to an aircraftoperable to transition between thrust-borne lift in a VTOL orientationand wing-borne lift in a biplane orientation. The aircraft includes anairframe having first and second wings with first and second pylonsextending therebetween. The first and second wings each have first andsecond outboard nacelle stations. A two-dimensional distributed thrustarray is attached to the airframe. The thrust array includes a pluralityof outboard propulsion assemblies coupled to the first and secondoutboard nacelle stations of the first and second wings. The thrustarray is operable to provide thrust for the aircraft. A flight controlsystem is coupled to the airframe and is operable to independentlycontrol a rotor speed and a thrust vector of each of the propulsionassemblies. In a low thrust to weight configuration of the aircraft,transitions from the VTOL orientation to the biplane orientation includeestablishing a pitch down flight attitude while engaging in collectivethrust vectoring of the outboard propulsion assemblies to maintain hoverstability followed by collectively reducing the thrust vector angles toinitiate forward flight followed by further collective reduction in thethrust vector angles and increasing the pitch down attitude until thethrust vectors and the wings are substantially horizontal. In a highthrust to weight configuration of the aircraft, transitions from theVTOL orientation to the biplane orientation include maintaining a levelflight attitude while collectively increasing the thrust vector anglesof the outboard propulsion assemblies to initiate forward flightfollowed by maintaining the thrust vector angles and increasing thepitch down attitude until the thrust vectors are substantiallyhorizontal followed by collectively reducing thrust vector angles andincreasing the pitch down attitude while maintaining the thrust vectorssubstantially horizontal until the wings are substantially horizontal.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the features and advantages of thepresent disclosure, reference is now made to the detailed descriptionalong with the accompanying figures in which corresponding numerals inthe different figures refer to corresponding parts and in which:

FIGS. 1A-1G are schematic illustrations of an aircraft operable totransition between thrust-borne lift in a VTOL orientation andwing-borne lift in a biplane orientation in accordance with embodimentsof the present disclosure;

FIGS. 2A-2I are schematic illustrations of the aircraft of FIG. 1 in asequential flight operating scenario in accordance with embodiments ofthe present disclosure;

FIG. 3 is a flow diagram of a process for prioritizing the use of flightattitude controls in accordance with embodiments of the presentdisclosure;

FIGS. 4A-4D are block diagram of various implementations of a thrustarray and flight control system for an aircraft in accordance withembodiments of the present disclosure;

FIGS. 5A-5C are schematic illustrations of various line replaceablepropulsion assemblies for an aircraft in accordance with embodiments ofthe present disclosure;

FIGS. 6A-6I are schematic illustrations of a propulsion assembly havinga two-axis gimbal for an aircraft in accordance with embodiments of thepresent disclosure;

FIGS. 7A-7C are schematic illustrations of a propulsion assembly havinga single-axis gimbal for an aircraft in accordance with embodiments ofthe present disclosure;

FIGS. 8A-8B are schematic illustrations of an aircraft operable totransition between thrust-borne lift in a VTOL orientation andwing-borne lift in a biplane orientation in accordance with embodimentsof the present disclosure;

FIGS. 9A-9B are schematic illustrations of an aircraft operable totransition between thrust-borne lift in a VTOL orientation andwing-borne lift in a biplane orientation in accordance with embodimentsof the present disclosure;

FIGS. 10A-10B are schematic illustrations of an aircraft operable totransition between thrust-borne lift in a VTOL orientation andwing-borne lift in a biplane orientation in accordance with embodimentsof the present disclosure;

FIGS. 11A-11D are schematic illustrations of a man portable aircraftsystem operable for rapid in-situ assembly in accordance withembodiments of the present disclosure;

FIG. 12 is a flow diagram of a process for automated configuration ofmission specific aircraft in accordance with embodiments of the presentdisclosure;

FIG. 13 is a block diagram of autonomous and remote control systems foran aircraft in accordance with embodiments of the present disclosure;

FIGS. 14A-14C are schematic illustrations of rapid connection interfacesoperable for use in coupling component parts of an aircraft inaccordance with embodiments of the present disclosure;

FIGS. 15A-15B are schematic illustrations of rapid connection interfacesoperable for use in coupling component parts of an aircraft inaccordance with embodiments of the present disclosure;

FIGS. 16A-16B are schematic illustrations of rapid connection interfacesoperable for use in coupling component parts of an aircraft inaccordance with embodiments of the present disclosure;

FIGS. 17A-17B are schematic illustrations of rapid connection interfacesoperable for use in coupling component parts of an aircraft inaccordance with embodiments of the present disclosure;

FIGS. 18A-18D are schematic illustrations of an aircraft operable tomaintain hover stability in inclined flight attitudes in accordance withembodiments of the present disclosure;

FIGS. 19A-19B are schematic illustrations of an aircraft operable totranslate and change altitude in level and inclined flight attitudes inaccordance with embodiments of the present disclosure;

FIGS. 20A-20D are schematic illustrations of an aircraft operable forexternal load operations in accordance with embodiments of the presentdisclosure;

FIGS. 21A-21E are schematic illustrations of an aircraft operable toperform transitions from a VTOL orientation to a biplane orientation ina low thrust to weight configuration in accordance with embodiments ofthe present disclosure; and

FIGS. 22A-22E are schematic illustrations of an aircraft operable toperform transitions from a VTOL orientation to a biplane orientation ina high thrust to weight configuration in accordance with embodiments ofthe present disclosure.

DETAILED DESCRIPTION

While the making and using of various embodiments of the presentdisclosure are discussed in detail below, it should be appreciated thatthe present disclosure provides many applicable inventive concepts,which can be embodied in a wide variety of specific contexts. Thespecific embodiments discussed herein are merely illustrative and do notdelimit the scope of the present disclosure. In the interest of clarity,not all features of an actual implementation may be described in thepresent disclosure. It will of course be appreciated that in thedevelopment of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedeveloper's specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming but would be a routine undertakingfor those of ordinary skill in the art having the benefit of thisdisclosure.

In the specification, reference may be made to the spatial relationshipsbetween various components and to the spatial orientation of variousaspects of components as the devices are depicted in the attacheddrawings. However, as will be recognized by those skilled in the artafter a complete reading of the present disclosure, the devices,members, apparatuses, and the like described herein may be positioned inany desired orientation. Thus, the use of terms such as “above,”“below,” “upper,” “lower” or other like terms to describe a spatialrelationship between various components or to describe the spatialorientation of aspects of such components should be understood todescribe a relative relationship between the components or a spatialorientation of aspects of such components, respectively, as the devicedescribed herein may be oriented in any desired direction. As usedherein, the term “coupled” may include direct or indirect coupling byany means, including moving and/or non-moving mechanical connections.

Referring to FIGS. 1A-1G in the drawings, various views of an aircraft10 operable to transition between thrust-borne lift in a VTOLorientation and wing-borne lift in a biplane orientation are depicted.FIGS. 1A, 1C, 1E depict aircraft 10 in the VTOL orientation wherein thepropulsion assemblies provide thrust-borne lift. FIGS. 1B, 1D, 1F depictaircraft 10 in the biplane orientation wherein the propulsion assembliesprovide forward thrust with the forward airspeed of aircraft 10providing wing-borne lift enabling aircraft 10 to have a high speedand/or high endurance forward flight mode. Aircraft 10 has alongitudinal axis 10 a that may also be referred to as the roll axis, alateral axis 10 b that may also be referred to as the pitch axis and avertical axis 10 c that may also be referred to as the yaw axis, as bestseen in FIGS. 1E and 1F. In the VTOL orientation, when longitudinal axis10 a and lateral axis 10 b are both in a horizontal plane and normal tothe local vertical in the earth's reference frame, aircraft 10 has alevel flight attitude. When at least one of longitudinal axis 10 a orlateral axis 10 b extends out of the horizontal plane, aircraft 10 hasan inclined flight attitude. For example, an inclined flight attitudemay be a nonzero pitch flight attitude such as a pitch down flightattitude or a pitch up flight attitude. This operation is depicted inFIG. 1E with aircraft 10 rotating about lateral axis 10 b, as indicatedby arrow 10 d. Similarly, an inclined flight attitude may be a nonzeroroll flight attitude such as a roll left flight attitude or a roll rightflight attitude. This operation is depicted in FIG. 1E with aircraft 10rotating about longitudinal axis 10 a, as indicated by arrow 10 e. Inaddition, an inclined flight attitude may include both a nonzero pitchflight attitude and a nonzero roll flight attitude.

Aircraft 10 is a mission configurable aircraft operable to provide highefficiency transportation for diverse payloads. Based upon missionparameter including flight parameters such as environmental conditions,speed, range and thrust requirements as well as payload parameters suchas size, shape, weight, type, durability and the like, aircraft 10 mayselectively incorporate a variety of propulsion assemblies havingdifferent characteristics and/or capacities. For example, the propulsionassemblies operable for use with aircraft 10 may have difference thrusttypes including different maximum thrust outputs and/or different thrustvectoring capabilities including non thrust vectoring propulsionassemblies, single-axis thrust vectoring propulsion assemblies such aslongitudinal thrust vectoring propulsion assemblies and/or lateralthrust vectoring propulsion assemblies and two-axis thrust vectoringpropulsion assemblies which may also be referred to as omnidirectionalthrust vectoring propulsion assemblies. In addition, various componentsof each propulsion assembly may be selectable including the power plantconfiguration and the rotor design. For example, the type or number ofbatteries in a propulsion assembly may be selected based upon the power,weight, endurance and/or temperature requirements of a mission.Likewise, the characteristics of the rotors assemblies may be selected,such as the number of rotor blades, the blade pitch, the blade twist,the rotor diameter, the chord distribution, the blade material and thelike.

In the illustrated embodiment, aircraft 10 includes an airframe 12including wings 14, 16 each having an airfoil cross-section thatgenerates lift responsive to the forward airspeed of aircraft 10. Wings14, 16 may be formed as single members or may be formed from multiplewing sections. The outer skins for wings 14, 16 are preferably formedfrom high strength and lightweight materials such as fiberglass, carbon,plastic, metal or other suitable material or combination of materials.As illustrated, wings 14, 16 are straight wings. In other embodiments,wings 14, 16 could have other designs such as polyhedral wing designs,swept wing designs or other suitable wing design. As best seen in FIG.1G, wing 14 has two pylon stations 14 a, 14 b and four nacelle stations14 c, 14 d, 14 e, 14 f. Likewise, wing 16 has two pylon stations 16 a,16 b and four nacelle stations 16 c, 16 d, 16 e, 16 f. Each of the pylonstations and each of the nacelle stations includes a rapid connectioninterface operable for mechanical and electrical connectivity, asdiscussed herein. Extending generally perpendicularly between wings 14,16 are two truss structures depicted as pylons 18, 20. Pylon 18 iscoupled between pylon stations 14 a, 16 a and preferably forms amechanical and electrical connection therebetween. Pylon 20 is coupledbetween pylon stations 14 b, 16 b and preferably forms a mechanical andelectrical connection therebetween. In other embodiments, more than twopylons may be present. Pylons 18, 20 are preferably formed from highstrength and lightweight materials such as fiberglass, carbon, plastic,metal or other suitable material or combination of materials. As bestseen in FIG. 1G, pylon 18 has a nacelle station 18 a and a payloadstation 18 b. Likewise, pylon 20 has a nacelle station 20 a and apayload station 20 b. Each of the nacelle stations and each of thepayload stations includes a rapid connection interface operable formechanical and electrical connectivity, as discussed herein. In theillustrated embodiment, as no propulsion assembly is coupled to eitherof pylons 18, 20, a nacelle station cover 18 c protects nacelle station18 a of pylon 18 and a nacelle station cover 20 c protects nacellestation 20 a of pylon 20.

Wings 14, 16 and pylons 18, 20 preferably include central passagewaysoperable to contain flight control systems, energy sources,communication lines and other desired systems. For example, as best seenin FIGS. 1C and 1D, pylon 20 houses the flight control system 22 ofaircraft 10. Flight control system 22 is preferably a redundant digitalflight control system including multiple independent flight controlcomputers. For example, the use of a triply redundant flight controlsystem 22 improves the overall safety and reliability of aircraft 10 inthe event of a failure in flight control system 22. Flight controlsystem 22 preferably includes non-transitory computer readable storagemedia including a set of computer instructions executable by one or moreprocessors for controlling the operation of aircraft 10. Flight controlsystem 22 may be implemented on one or more general-purpose computers,special purpose computers or other machines with memory and processingcapability. For example, flight control system 22 may include one ormore memory storage modules including, but is not limited to, internalstorage memory such as random access memory, non-volatile memory such asread only memory, removable memory such as magnetic storage memory,optical storage, solid-state storage memory or other suitable memorystorage entity. Flight control system 22 may be a microprocessor-basedsystem operable to execute program code in the form ofmachine-executable instructions. In addition, flight control system 22may be selectively connectable to other computer systems via aproprietary encrypted network, a public encrypted network, the Internetor other suitable communication network that may include both wired andwireless connections.

Wings 14, 16 and pylons 18, 20 may contain one or more of electricalpower sources depicted as one or more batteries 22 a in pylon 20, asbest seen in FIGS. 1C and 1D. Batteries 22 a supply electrical power toflight control system 22. In some embodiments, batteries 22 a may beused to supply electrical power for the distributed thrust array ofaircraft 10. Wings 14, 16 and pylons 18, 20 also contain a communicationnetwork including the electrical interfaces of the pylon stations, thenacelle stations and the payload stations that enables flight controlsystem 22 to communicate with the distributed thrust array of aircraft10. In the illustrated embodiment, aircraft 10 has a two-dimensionaldistributed thrust array that is coupled to airframe 12. As used herein,the term “two-dimensional thrust array” refers to a plurality of thrustgenerating elements that occupy a two-dimensional space in the form of aplane. A minimum of three thrust generating elements is required to forma “two-dimensional thrust array.” A single aircraft may have more thanone “two-dimensional thrust arrays” if multiple groups of at least threethrust generating elements each occupy separate two-dimensional spacesthus forming separate planes. As used herein, the term “distributedthrust array” refers to the use of multiple thrust generating elementseach producing a portion of the total thrust output. The use of a“distributed thrust array” provides redundancy to the thrust generationcapabilities of the aircraft including fault tolerance in the event ofthe loss of one of the thrust generating elements. A “distributed thrustarray” can be used in conjunction with a “distributed power system” inwhich power to each of the thrust generating elements is supplied by alocal power system instead of a centralized power source. For example,in a “distributed thrust array” having a plurality of propulsionassemblies acting as the thrust generating elements, a “distributedpower system” may include individual battery elements housed within thenacelle of each propulsion assemblies.

The two-dimensional distributed thrust array of aircraft 10 includes aplurality of inboard propulsion assemblies, individually andcollectively denoted as 24 and a plurality of outboard propulsionassemblies, individually and collectively denoted as 26. Inboardpropulsion assemblies 24 are respectively coupled to nacelle stations 14e, 14 f of wing 14 and nacelle stations 16 e, 16 f of wing 16 andpreferably form mechanical and electrical connections therewith.Outboard propulsion assemblies 26 are respectively coupled to nacellestations 14 c, 14 d of wing 14 and nacelle stations 16 c, 16 d of wing16 and preferably form mechanical and electrical connections therewith.In some embodiments, inboard propulsion assemblies 24 could form a firsttwo-dimensional distributed thrust array and outboard propulsionassemblies 26 could form a second two-dimensional distributed thrustarray. In other embodiments, inboard propulsion assemblies 24 andoutboard propulsion assemblies 26 could form a single two-dimensionaldistributed thrust array.

In the illustrated embodiment, inboard propulsion assemblies 24 andoutboard propulsion assemblies 26 have difference thrust types. Forexample, outboard propulsion assemblies 26, individual and collectively,may have a higher maximum thrust output than inboard propulsionassemblies 24. Alternatively or additionally, outboard propulsionassemblies 26 may be variable speed propulsion assemblies while inboardpropulsion assemblies 24 may be single speed propulsion assemblies. Inthe illustrated embodiment, inboard propulsion assemblies 24 are fixedpitch, variable speed, non thrust vectoring propulsion assemblies whileoutboard propulsion assemblies 26 are fixed pitch, variable speed,omnidirectional thrust vectoring propulsion assemblies. In this regard,inboard propulsion assemblies 24 and outboard propulsion assemblies 26each form a two-dimensional distributed thrust array of a differentthrust type. Specifically, inboard propulsion assemblies 24 may bereferred to as a two-dimensional distributed thrust array of non thrustvectoring propulsion assemblies. Likewise, outboard propulsionassemblies 26 may be referred to as a two-dimensional distributed thrustarray of omnidirectional thrust vectoring propulsion assemblies.Including a two-dimensional distributed thrust array of omnidirectionalthrust vectoring propulsion assemblies on aircraft 10 enables aircraft10 to maintain hover stability when aircraft 10 is in a level orinclined flight attitude state. In addition, the use of atwo-dimensional distributed thrust array of omnidirectional thrustvectoring propulsion assemblies on aircraft 10 enables aircraft 10 totranslate and/or change altitude while maintaining a level or inclinedflight attitude or while changing the flight attitude state of aircraft10.

As illustrated, outboard propulsion assemblies 26 are coupled to theoutboard ends of wings 14, 16, inboard propulsion assemblies 24 arecoupled to wing 14 in a high wing configuration and inboard propulsionassemblies 24 are coupled to wing 16 in a low wing configurations.Propulsion assemblies 24, 26 are independently attachable to anddetachable from airframe 12 such that aircraft 10 may be part of a manportable aircraft system having component parts with connection featuresdesigned to enable rapid in-situ assembly. Alternatively or additional,the various components of aircraft 10 including the flight controlsystem, the wings, the pylons and the propulsion assemblies may beselected by an aircraft configuration computing system based uponmission specific parameters. This may be enabled, in part, by usingpropulsion assemblies 24, 26 that are standardized and/orinterchangeable units and preferably line replaceable units providingeasy installation and removal from airframe 12. As discussed herein,propulsion assemblies 24, 26 may be coupled to the nacelle stations ofwings 14, 16 using rapid connection interfaces to form structural andelectrical connections.

For example, the structural connections may include high speed fasteningelements, cam and hook connections, pin connections, quarter turn latchconnections, snap connections, magnetic connections or electromagneticconnections which may also be remotely releasable connections. Theelectrical connections may include forming communication channelsincluding redundant communication channels or triply redundantcommunication channels. In addition, the use of line replaceablepropulsion units is beneficial in maintenance situations if a fault isdiscovered with one of the propulsion assemblies 24, 26. In this case,the faulty propulsion assemblies 24, 26 can be decoupled from airframe12 by simple operations and another propulsion assemblies 24, 26 canthen be attached to airframe 12. In other embodiments, propulsionassemblies 24, 26 may be permanently coupled to wings 14, 16 byriveting, bonding and/or other suitable technique.

As best seen in FIG. 1A, each inboard propulsion assembly 24 includes anacelle 24 a that houses components including a battery 24 b, anelectronic speed controller 24 c, an electronics node 24 d, sensors andother desired electronic equipment. Nacelle 24 a also supports apropulsion system 24 e depicted as an electric motor 24 f and a rotorassembly 24 g. Each outboard propulsion assembly 26 includes a nacelle26 a that houses components including a battery 26 b, an electronicspeed controller 26 c, gimbal actuators 26 d, an aerosurface actuator 26e, an electronics node 26 f, sensors and other desired electronicequipment. Nacelle 26 a also supports a two-axis gimbal 26 g, apropulsion system 26 h depicted as an electric motor 26 i and a rotorassembly 26 j and aerosurfaces 26 k. As the power for each propulsionassembly 24, 26 is provided by batteries housed within the respectivenacelles, aircraft 10 has a distributed power system for the distributedthrust array. Alternatively or additionally, electrical power may besupplied to the electric motors and/or the batteries disposed with thenacelles from batteries 22 a carried by airframe 12 via thecommunications network. In other embodiments, the propulsion assembliesmay include internal combustion engines or hydraulic motors. In theillustrated embodiment, aerosurfaces 26 k of outboard propulsionassembly 26 are active aerosurfaces that serve as horizontalstabilizers, elevators to control the pitch and/or angle of attack ofwings 14, 16 and/or ailerons to control the roll or bank of aircraft 10in the biplane orientation of aircraft 10 and serve to enhance hoverstability in the VTOL orientation of aircraft 10.

Flight control system 22 communicates via the wired communicationsnetwork of airframe 12 with the electronics nodes 24 d, 26 f of thepropulsion assemblies 24, 26. Flight control system 22 receives sensordata from and sends flight command information to the electronics nodes24 d, 26 f such that each propulsion assembly 24, 26 may be individuallyand independently controlled and operated. For example, flight controlsystem 22 is operable to individually and independently control thespeed of each propulsion assembly 24. In addition, flight control system22 is operable to individually and independently control the speed, thethrust vector and the position of the aerosurfaces of each propulsionassembly 26. Flight control system 22 may autonomously control some orall aspects of flight operation for aircraft 10. Flight control system22 is also operable to communicate with remote systems, such as a groundstation via a wireless communications protocol. The remote system may beoperable to receive flight data from and provide commands to flightcontrol system 22 to enable remote flight control over some or allaspects of flight operation for aircraft 10. The autonomous and/orremote operation of aircraft 10 enables aircraft 10 to perform unmannedlogistic operations for both military and commercial applications.

Each propulsion assembly 24, 26 includes a rotor assembly 24 g, 26 jthat is coupled to an output drive of a respective electrical motor 24f, 26 i that rotates the rotor assembly 24 g, 26 j in a rotational planeto generate thrust for aircraft 10. In the illustrated embodiment, rotorassemblies 24 g, 26 j each include two rotor blades having a fixedpitch. In other embodiments, the rotor assemblies could have othernumbers of rotor blades including rotor assemblies having three or morerotor blades. Alternatively or additionally, the rotor assemblies couldhave variable pitch rotor blades with collective and/or cyclic pitchcontrol. Each electrical motor 24 f is paired with a rotor assembly 24 gto form a propulsion system 24 e. In the illustrated embodiment, eachpropulsion system 24 e is secured to a nacelle 24 a without a tiltingdegree of freedom such that propulsion assemblies 24 are non thrustvectoring propulsion assemblies. Each electrical motor 26 i is pairedwith a rotor assembly 26 j to form a propulsion system 26 h. Asdescribed herein, each propulsion system 26 h has a two-axis tiltingdegree of freedom relative to nacelle 26 a provided by two-axis gimbal26 g such that propulsion assemblies 26 are omnidirectional thrustvectoring propulsion assemblies. In the illustrated embodiment, themaximum angle of the thrust vector may preferably be between about 10degrees and about 30 degrees, may more preferably be between about 15degrees and about 25 degrees and may most preferably be about 20degrees. Notably, using a 20-degree thrust vector yields a lateralcomponent of thrust that is about 34 percent of total thrust. In otherembodiments, the inboard and/or the outboard propulsion systems may havea single-axis tilting degree of freedom in which case, the propulsionassemblies could act as longitudinal and/or lateral thrust vectoringpropulsion assemblies.

Aircraft 10 may operate as a transport aircraft for a payload 30 that isfixed to or selectively attachable to and detachable from airframe 12.In the illustrated embodiment, payload 30 is selectively couplablebetween payload stations 18 b, 20 b of pylons 18, 20 preferably forminga mechanical and electrical connection therebetween. Payload 30 maycarry, include or be integral with a variety of modules such as apackage delivery module, an air reconnaissance module, a light detectionand ranging module, a camera module, an optical targeting module, alaser module, a sensors module, an air-to-ground weapons module, anair-to-air weapons module, a communications module and/or a cargo hookmodule or the like depending upon the mission being perform by aircraft10. The connection between payload stations 18 b, 20 b and payload 30may be a fixed connection that secures payload 30 in a single locationrelative to airframe 12. Alternatively, payload 30 may be allowed torotate and/or translate relative to airframe 12 during ground and/orflight operations. For example, it may be desirable to have payload 30low to the ground for loading and unloading cargo but more distant fromthe ground for takeoff and landing. As another example, it may bedesirable to change the center of mass of aircraft 10 during certainflight conditions such as moving payload 30 forward relative to airframe12 during high speed flight in the biplane orientation. Similarly, itmay be desirable to adjust the center of mass of aircraft 10 by loweringpayload 30 relative to airframe 12 during hover. As illustrated, payload30 may be selectively coupled to and decoupled from airframe 12 toenable sequential pickup, transportation and delivery of multiplepayloads 30 to and from multiple locations.

Airframe 12 preferably has remote release capabilities of payload 30.For example, this feature allows airframe 12 to drop payload 30 or cargocarried by payload 30 at a desired location following transportation. Inaddition, this feature allows airframe 12 to jettison payload 30 duringflight, for example, in the event of an emergency situation such as apropulsion assembly or other system of aircraft 10 becoming compromised.One or more communication channels may be established between payload 30and airframe 12 when payload 30 is attached therewith such that flightcontrol system 22 may send commands to payload 30 to perform functions.For example, flight control system 22 may operate doors and othersystems of a package delivery module; start and stop aerial operationsof an air reconnaissance module, a light detection and ranging module, acamera module, an optical targeting module, a laser module or a sensorsmodule; launch missiles from an air-to-ground weapons module or anair-to-air weapons module; and/or deploy and recover items using a cargohook module.

Referring additionally to FIGS. 2A-2I in the drawings, a sequentialflight-operating scenario of aircraft 10 is depicted. In the illustratedembodiment, payload 30 is attached to airframe 12 and may contain adesired cargo or module. It is noted, however, that payload 30 may beselectively disconnected from airframe 12 such that a single airframecan be operably coupled to and decoupled from numerous payloads fornumerous missions over time. In addition, aircraft 10 may performmissions without having a payload 30 attached to airframe 12. As bestseen in FIG. 2A, aircraft 10 is in a tailsitting position on the ground.When aircraft 10 is ready for a mission, flight control system 22commences operations to provide flight control to aircraft 10 which maybe autonomous flight control, remote flight control or a combinationthereof. For example, it may be desirable to utilize remote flightcontrol during certain maneuvers such as takeoff and landing but rely onautonomous flight control during hover, high speed forward flight and/ortransitions between wing-borne flight and thrust-borne flight.

As best seen in FIG. 2B, aircraft 10 has performed a vertical takeoffand is engaged in thrust-borne lift with payload 30 lifted into the air.As illustrated, rotor assemblies 24 g of propulsion assemblies 24 areeach rotating in the same horizontal plane forming a firsttwo-dimensional distributed thrust array. Likewise, rotor assemblies 26j of propulsion assemblies 26 are each rotating in the same horizontalplane forming a second two-dimensional distributed thrust array. Aslongitudinal axis 10 a and lateral axis 10 b (denoted as the target) areboth in a horizontal plane H, normal to the local vertical in theearth's reference frame, aircraft 10 has a level flight attitude. Asdiscussed herein, flight control system 22 independently controls andoperates each propulsion assembly 24, 26 including independentlycontrolling speed, thrust vector and aerosurface position. During hover,flight control system 22 may utilize speed control, thrust vectoringand/or aerosurface maneuvers of selected propulsion assemblies 26 forproviding hover stability for aircraft 10 and for providing pitch, roll,yaw and translation authority for aircraft 10. As used herein, the term“hover stability” refers to remaining in one place in the air whilemaintaining a generally or substantially static flight attitude.

For example, flight control system 22 is operable to maintain or changethe flight attitude of aircraft 10 by prioritizing the use of flightattitude controls based upon flight attitude control authority asdescribed with reference to FIG. 3. As used herein, the term “flightattitude control” refers to mechanisms used to impart change to ormaintain the current flight attitude state of aircraft 10. For example,the flight attitude controls include the use of thrust vectoring, rotorspeed, aerosurface position, combinations thereof and the like of one ormore of the propulsion assemblies. As used herein, the term “flightattitude control authority” refers to the effectiveness and/orresponsiveness of a flight attitude control to impart change to ormaintain the current flight attitude state of aircraft 10. In process50, flight control system 22 is configured to determine and maintain anoptimal flight attitude state for aircraft 10. During flight, flightcontrol system 22 performs continuous analysis of the mission parametersand the current flight conditions to determine the optimal flightattitude state for the aircraft, as indicated in block 52. This analysisdetermines, for example, whether the aircraft is in the VTOLorientation, the biplane orientation or some transitory orientationtherebetween; whether a level flight attitude or an inclined flightattitude is desired; whether a stable flight attitude or a changingflight attitude is desired; and/or whether hover, translation, altitudechange and/or direction change is desired and the rate at which suchchange may be desired.

In block 54, flight control system 22 monitors the current flightattitude state of the aircraft. Data for this analysis may be providedfrom a sensor suite carried by airframe 12, propulsion assemblies 24, 26and/or payload 30 including, for example, an attitude and headingreference system (AHRS) with solid-state or microelectromechanicalsystems (MEMS) gyroscopes, accelerometers and magnetometers. Based uponthe optimal flight attitude state for the aircraft and the currentflight attitude state of the aircraft, flight control system 22identifies any deviations between the current flight attitude state andthe optimal flight attitude state in block 56. For example, this processmay identify deviations between a current pitch state and an optimalpitch state of the aircraft, deviations between a current roll state andan optimal roll state of the aircraft, deviations between a current yawstate and an optimal yaw state of the aircraft and/or combinationthereof. This process may also involve determining a cause of thedeviation such as identifying the occurrence of a flight anomaly such asturbulence, a bird strike, a component fault, a one engine inoperablecondition or the like.

If a deviation is identified, flight control system 22 determines anorder for the flight attitude controls of the aircraft based upon theflight attitude control authority of each of the flight attitudecontrols in the current flight attitude state, in block 58. This processinvolves selecting the order in which the possible the flight attitudecontrols, for example, thrust vectoring, rotor speed and aerosurfaceposition of each of the propulsion assemblies, should be used based uponthe expected effectiveness and/or responsiveness of using a specificflight attitude control or a combination of flight attitude controls.The process considers the current state of each flight attitude control,the available envelope of each flight attitude control and the expectedaircraft response to each flight attitude control. The process alsoconsiders the orientation of the aircraft. For example, in the VTOLorientation, changes in thrust vector and/or rotor speed of selectedpropulsion assemblies may create a more desired aircraft response thanchanges in aerosurface position, such as a response of a greatermagnitude, a response with a greater rate of change and/or a responsewith a greater rate of rate of change. Similarly, in the biplaneorientation, changes in aerosurface position and/or rotor speed ofselected propulsion assemblies may create a more desired aircraftresponse than changes in thrust vector.

In block 60, flight control system 22 implements the highest orderflight attitude control to bias the aircraft from the current flightattitude state to the optimal flight attitude state. This processresults in the use of the selected flight attitude control of thrustvectoring, rotor speed, aerosurface position and/or combinations thereoffor one or more of the propulsion assemblies. Importantly, in thisprocess, the highest order flight attitude control is not limited to asingle type of flight attitude control such as thrust vectoring, rotorspeed or aerosurface position. Instead, flight control system 22 isoperable to evaluate combinations and/or permutations of thrustvectoring, rotor speed, aerosurface position of the propulsionassemblies to formulate the highest order flight attitude controlavailable to yield the desired aircraft response toward the optimalflight attitude state. For example, the highest order flight attitudecontrol may involve a change in the thrust vector but no change in rotorspeed or aerosurface position of some or all of outboard propulsionassemblies 26 along with no change in the operation of any of inboardpropulsion assemblies 24. As another example, the highest order flightattitude control may involve a change in the rotor speed and aerosurfaceposition but no change in the thrust vector of some or all of outboardpropulsion assemblies 26 along with a change in the rotor speed of someor all of inboard propulsion assemblies 24. Based upon these examples,those skilled in the art should understand that a large variety offlight attitude controls are available to aircraft 10 that must beevaluated by flight control system 22 to prioritize the order of usethereof. In block 62, flight control system 22 senses the aircraftresponse to the implementation of the highest order flight attitudecontrol to determine whether the aircraft transitioned from the currentflight attitude state to the optimal flight attitude state using data,for example, from the attitude and heading reference system. In block64, flight control system 22 determines whether the aircraft responsewas consistent with the expected aircraft response. This process mayinclude determining a cause of any deviation between the actual aircraftresponse and the expected aircraft response such as identification of afault in one of the flight attitude controls. For example, this processmay determine whether the thrust vectoring, rotor speed or aerosurfacepositioning capability of a propulsion assembly failed. If the aircraftresponse is consistent with the expected aircraft response, the processmay return to block 52 as flight control system 22 continuously performsthis function. If the aircraft response was not consistent with theexpected aircraft response, in block 66, flight control system 22implements the next highest order flight attitude control to bias theaircraft from the current flight attitude state to the optimal flightattitude state. This process will take into account any faultsidentified in any flight attitude control to formulate the next highestorder flight attitude control. The processes of block 64 and block 66may be repeated until the optimal flight attitude state is achieved.

Returning to the sequential flight-operating scenario of aircraft 10 inFIGS. 2A-2I, after vertical assent to the desired elevation, aircraft 10may begin the transition from thrust-borne lift to wing-borne lift. Asbest seen from the progression of FIGS. 2B-2E, aircraft 10 is operableto pitch down from the VTOL orientation toward the biplane orientationto enable high speed and/or long range forward flight. As seen in FIG.2C, longitudinal axis 10 a extends out of the horizontal plane H suchthat aircraft 10 has an inclined flight attitude of about thirty degreespitch down. As seen in FIG. 2D, longitudinal axis 10 a extends out ofthe horizontal plane H such that aircraft 10 has an inclined flightattitude of about sixty degrees pitch down. Flight control system 22 mayachieve this operation through speed control of some or all ofpropulsion assemblies 24, 26, collective thrust vectoring of propulsionassemblies 26, collective maneuvers of aerosurfaces 26 k or anycombination thereof. As discussed herein, the specific procedure usedfor VTOL to biplane transitions may be depend upon the thrust to weightconfiguration of aircraft 10.

As best seen in FIG. 2E, rotor assemblies 24 g of propulsion assemblies24 are each rotating in the same vertical plane forming a firsttwo-dimensional distributed thrust array. Likewise, rotor assemblies 26j of propulsion assemblies 26 are each rotating in the same verticalplane forming a second two-dimensional distributed thrust array. Byconvention, longitudinal axis 10 a has been reset to be in thehorizontal plane H, which also includes lateral axis 10 b, such thataircraft 10 has a level flight attitude in the biplane orientation. Asforward flight with wing-borne lift requires significantly less powerthen VTOL flight with thrust-borne lift, the operating speed of some orall of the propulsion assemblies 24, 26 may be reduced. In certainembodiments, some of the propulsion assemblies 24, 26 of aircraft 10could be shut down during forward flight. In the biplane orientation,the independent control provided by flight control system 22 over eachpropulsion assembly 24, 26 provides pitch, roll and yaw authority usingcollective or differential thrust vectoring, differential speed control,collective or differential aerosurface maneuvers or any combinationthereof. As aircraft 10 approaches its destination, aircraft 10 maybegin its transition from wing-borne lift to thrust-borne lift. As bestseen from the progression of FIGS. 2E-2H, aircraft 10 is operable topitch up from the biplane orientation to the VTOL orientation to enable,for example, a vertical landing operation. As seen in FIG. 2F,longitudinal axis 10 a extends out of the horizontal plane H such thataircraft 10 has an inclined flight attitude of about thirty degreespitch up. As seen in FIG. 2G, longitudinal axis 10 a extends out of thehorizontal plane H such that aircraft 10 has an inclined flight attitudeof about sixty degrees pitch up. Flight control system 22 may achievethis operation through speed control of some or all of propulsionassemblies 24, 26, collective thrust vectoring of propulsion assemblies26, collective maneuvers of aerosurfaces 26 k or any combinationthereof. In FIG. 2H, aircraft 10 has completed the transition from thebiplane orientation to the VTOL orientation and, by convention,longitudinal axis 10 a has been reset to be in the horizontal plane Hwhich also includes lateral axis 10 b such that aircraft 10 has a levelflight attitude in the VTOL orientation. Once aircraft 10 has completedthe transition to the VTOL orientation, aircraft 10 may commence itsvertical descent to a surface. As best seen in FIG. 2I, aircraft 10 haslanding in a tailsitting orientation at the destination location andmay, for example, remotely drop payload 30.

Referring next to FIGS. 4A-4D, a mission configurable aircraft havingmultiple thrust array configurations will now be described. FIG. 4Adepicts the thrust array configuration of aircraft 10 in FIGS. 1A-1G.Specifically, aircraft 10 includes four outboard propulsion assemblies26 that form a two-dimensional thrust array of omnidirectional thrustvectoring propulsion assemblies. Propulsion assemblies 26 each includean electronics node depicted as including controllers, sensors and oneor more batteries, a two-axis gimbal operated by a pair of actuators anda propulsion system including an electric motor and a rotor assembly.The flight control system 22 is operably associated with propulsionassemblies 26 and is communicably linked to the electronic nodes thereofby a communications network depicted as the arrows between flightcontrol system 22 and propulsion assemblies 26. Flight control system 22receives sensor data from and sends commands to propulsion assemblies 26to enable flight control system 22 to independently control each ofpropulsion assemblies 26 as discussed herein.

An embodiment of an omnidirectional thrust vectoring propulsionassemblies 26 is depicted in FIG. 5A. Propulsion assembly 26 includes anacelle 26 a and a gimbal 26 g that is coupled to nacelle 26 a. Gimbal26 g includes an outer gimbal member 261 and an inner gimbal member 26m. Outer gimbal member 261 is pivotally coupled to nacelle 26 a and isoperable to tilt about a first axis. Inner gimbal member 26 m ispivotally coupled to outer gimbal member 261 and is operable to tiltabout a second axis that is orthogonal to the first axis. In theillustrated embodiment, actuator 26 n is coupled between nacelle 26 aand outer gimbal member 261 such that operation of actuator 26 n shiftlinkage 26 o to tilt outer gimbal member 261 about the first axisrelative to nacelle 26 a. Actuator 26 p is coupled between nacelle 26 aand inner gimbal member 26 m such that operation of actuator 26 p shiftslinkage 26 q to tilt inner gimbal member 26 m about the second axisrelative to outer gimbal member 261 and nacelle 26 a. A propulsionsystem 26 h is coupled to and is operable to tilt with gimbal 26 g aboutboth axes relative to nacelle 26 a. In the illustrated embodiment, therotor assembly has been removed from propulsion system 26 h such thatonly electric motor 26 i is visible.

The operation of an omnidirectional thrust vectoring propulsionassemblies 26 will now be described with reference to FIGS. 6A-6I. Inone example, propulsion assemblies 26 are operable to provide aircraft10 with control authority to translate in the longitudinal direction,fore-aft along longitudinal axis 10 a in FIG. 1E, during a stable hover.The achieve this, flight control system 22 sends commands to operateactuators 26 n to collectively tilt each of propulsion systems 26 h inthe forward or aft direction while having actuators 26 p in anunactuated state. In this configuration, propulsion assemblies 26generate thrust vectors having a forward or aftward directedlongitudinal component. In a stable hover, such collective thrustvectoring of propulsion assemblies 26 provides longitudinal controlauthority to aircraft 10. As best seen in the comparison of FIGS. 6A-6C,actuator 26 n is operated to tilt propulsion system 26 h longitudinallybetween a fully forward configuration shown in FIG. 6A and a fully aftconfiguration shown in FIG. 6C as well as in an infinite number ofpositions therebetween including the fully vertical configuration shownin FIG. 6B. This operation longitudinally shifts the thrust vector ofpropulsion assembly 26 to enable the longitudinal control authority ofaircraft 10. The maximum longitudinal tilt angle of gimbal 26 g maypreferably be between about 10 degrees and about 30 degrees, may morepreferably be between about 15 degrees and about 25 degrees and may mostpreferably be about 20 degrees. As should be understood by those havingordinary skill in the art, the magnitude of the longitudinal componentof the thrust vector is related to the direction of the thrust vector,which is determined by the longitudinal tilt angle of gimbal 26 g.

If it is desired to translate aircraft 10 in the lateral direction,right-left along lateral axis 10 b in FIG. 1E, flight control system 22sends commands to operate actuators 26 p to collectively tilt each ofpropulsion systems 26 h in the right or left direction while havingactuators 26 n in an unactuated state. In this configuration, propulsionassemblies 26 generate thrust vectors having a rightward or leftwarddirected lateral component. In a stable hover, such collective thrustvectoring of propulsion assemblies 26 provides lateral control authorityto aircraft 10. As best seen in the comparison of FIGS. 6D-6F, actuator26 p is operated to tilt propulsion system 26 h laterally between afully right configuration shown in FIG. 6D and a fully leftconfiguration shown in FIG. 6F as well as in an infinite number ofpositions therebetween including the fully vertical configuration shownin FIG. 6E. This operation laterally shifts the thrust vector ofpropulsion assembly 26 to enable the lateral control authority ofaircraft 10. The maximum lateral tilt angle of gimbal 26 g maypreferably be between about 10 degrees and about 30 degrees, may morepreferably be between about 15 degrees and about 25 degrees and may mostpreferably be about 20 degrees. As should be understood by those havingordinary skill in the art, the magnitude of the lateral component of thethrust vector is related to the direction of the thrust vector, which isdetermined by the lateral tilt angle of gimbal 26 g. Using both thelongitudinal and lateral control authority provided by collective thrustvectoring of propulsion assemblies 26, provides omnidirectionaltranslational control authority for aircraft 10 in a stable hover. If itis desired to translate aircraft 10 in a direction between thelongitudinal and lateral directions, such as in a diagonal direction,flight control system 22 sends commands to operate actuators 26 n tocollectively tilt each of propulsion systems 26 h in the forward or aftdirection and sends commands to operate actuators 26 p to collectivelytilt each of propulsion systems 26 h in the right or left direction. Inthis configuration, propulsion assemblies 26 generate thrust vectorshaving a forward or aftward directed longitudinal component and arightward or leftward directed lateral component. In a stable hover,such collective thrust vectoring of propulsion assemblies 26 providesomnidirectional translational control authority to aircraft 10. As bestseen in the comparison of FIGS. 6G-6I, actuators 26 n, 26 p are operatedto tilt propulsion system 26 h diagonally between a fully aft/rightconfiguration shown in FIG. 6G and a fully forward/left configurationshown in FIG. 6I as well as in an infinite number of positionstherebetween including the fully vertical configuration shown in FIG.6H. This operation shifts the thrust vector of propulsion assembly 26 toenable the omnidirectional control authority of aircraft 10.

Referring again to FIG. 4A, aircraft 10 includes four inboard propulsionassemblies 24 that form a two-dimensional thrust array of non thrustvectoring propulsion assemblies. Propulsion assemblies 24 each includean electronics node depicted as including controllers, sensors and oneor more batteries and a propulsion system including an electric motorand a rotor assembly. The flight control system 22 is operablyassociated with propulsion assemblies 24 and is communicably linked tothe electronic nodes thereof by a communications network depicted as thearrows between flight control system 22 and propulsion assemblies 24.Flight control system 22 receives sensor data from and sends commands topropulsion assemblies 24 to enable flight control system 22 toindependently control each of propulsion assemblies 24 as discussedherein. An embodiment of a non thrust vectoring propulsion assemblies 24is depicted in FIG. 5B. Propulsion assembly 24 includes a nacelle 24 aand a propulsion system 24 e that is coupled to nacelle 24 a. In theillustrated embodiment, the rotor assembly has been removed frompropulsion system 24 e such that only electric motor 24 f is visible.Thus, the thrust array configuration of aircraft 10 depicted in FIG. 4Aincludes inboard propulsion assemblies 24 having a first thrust type,non thrust vectoring, and outboard propulsion assemblies 26 having asecond thrust type, omnidirectional thrust vectoring.

FIG. 4B depicts another embodiment of a thrust array configuration ofaircraft 10. Specifically, aircraft 10 includes four outboard propulsionassemblies 26 that form a two-dimensional thrust array ofomnidirectional thrust vectoring propulsion assemblies. Propulsionassemblies 26 each include an electronics node depicted as includingcontrollers, sensors and one or more batteries, a two-axis gimbaloperated by a pair of actuators and a propulsion system including anelectric motor and a rotor assembly. The flight control system 22 isoperably associated with propulsion assemblies 26 and is communicablylinked to the electronic nodes thereof by a communications networkdepicted as the arrows between flight control system 22 and propulsionassemblies 26. Flight control system 22 receives sensor data from andsends commands to propulsion assemblies 26 to enable flight controlsystem 22 to independently control each of propulsion assemblies 26 asdiscussed herein. In addition, aircraft 10 includes four inboardpropulsion assemblies 36 that form a two-dimensional thrust array ofsingle-axis thrust vectoring propulsion assemblies. Propulsionassemblies 36 each include an electronics node depicted as includingcontrollers, sensors and one or more batteries, a single-axis gimbaloperated by an actuator and a propulsion system including an electricmotor and a rotor assembly. The flight control system 22 is operablyassociated with propulsion assemblies 36 and is communicably linked tothe electronic nodes thereof by a communications network depicted as thearrows between flight control system 22 and propulsion assemblies 36.Flight control system 22 receives sensor data from and sends commands topropulsion assemblies 36 to enable flight control system 22 toindependently control each of propulsion assemblies 36 as discussedherein. Thus, the thrust array configuration of aircraft 10 depicted inFIG. 4B includes inboard propulsion assemblies 36 having a first thrusttype, single-axis thrust vectoring, and outboard propulsion assemblies26 having a second thrust type, omnidirectional thrust vectoring.

An embodiment of a single-axis thrust vectoring propulsion assemblies 36is depicted in FIG. 5C. Propulsion assembly 36 includes a nacelle 36 aand a gimbal 36 b that is pivotally coupled to nacelle 36 a and isoperable to tilt about a single axis. In the illustrated embodiment,actuator 36 c is coupled between nacelle 36 a and gimbal 36 b such thatoperation of actuator 36 c shifts linkage 36 d to tilt gimbal 36 b aboutthe axis relative to nacelle 36 a. A propulsion system 36 e is coupledto and is operable to tilt with gimbal 36 b about the axis relative tonacelle 36 a. In the illustrated embodiment, the rotor assembly has beenremoved from propulsion system 36 e such that only electric motor 36 fis visible.

The operation of a single-axis thrust vectoring propulsion assemblies 36will now be described with reference to FIGS. 7A-7C. Propulsionassemblies 36 are operable to provide aircraft 10 with control authorityto translate in either the longitudinal direction or the lateraldirection during a stable hover depending upon the direction of thesingle-axis of propulsion assemblies 36. Accordingly, propulsionassemblies 36 may be referred to herein as longitudinal thrust vectoringpropulsion assemblies or lateral thrust vectoring propulsion assembliesdepending upon their orientation relative to the axes of aircraft 10.For illustrative purposes, propulsion assemblies 36 will be described aslongitudinal thrust vectoring propulsion assemblies in FIGS. 7A-7C. Ifit is desired to translate aircraft 10 in the longitudinal direction,fore-aft along longitudinal axis 10 a, flight control system 22 sendscommands to operate actuators 36 c to collectively tilt each ofpropulsion systems 36 e in the forward or aft direction. In thisconfiguration, propulsion assemblies 36 generate thrust vectors having aforward or aftward directed longitudinal component. In a stable hover,such collective thrust vectoring of propulsion assemblies 36 provideslongitudinal control authority to aircraft 10. As best seen in thecomparison of FIGS. 7A-7C, actuator 36 c is operated to tilt propulsionsystem 36 e longitudinally between a fully forward configuration shownin FIG. 7A and a fully aft configuration shown in FIG. 7C as well as inan infinite number of positions therebetween including the fullyvertical configuration shown in FIG. 7B. This operation longitudinallyshifts the thrust vector of propulsion assembly 36 to enable thelongitudinal control authority of aircraft 10. The maximum longitudinaltilt angle of gimbal 36 b may preferably be between about 10 degrees andabout 30 degrees, may more preferably be between about 15 degrees andabout 25 degrees and may most preferably be about 20 degrees. As shouldbe understood by those having ordinary skill in the art, the magnitudeof the longitudinal component of the thrust vector is related to thedirection of the thrust vector, which is determined by the longitudinaltilt angle of gimbal 36 b.

FIG. 4C depicts another embodiment of a thrust array configuration ofaircraft 10. Specifically, aircraft 10 includes four outboard propulsionassemblies 36 that form a two-dimensional thrust array of single-axisthrust vectoring propulsion assemblies, either longitudinal thrustvectoring propulsion assemblies or lateral thrust vectoring propulsionassemblies. Propulsion assemblies 36 each include an electronics nodedepicted as including controllers, sensors and one or more batteries, asingle-axis gimbal operated by an actuator and a propulsion systemincluding an electric motor and a rotor assembly. The flight controlsystem 22 is operably associated with propulsion assemblies 36 and iscommunicably linked to the electronic nodes thereof by a communicationsnetwork depicted as the arrows between flight control system 22 andpropulsion assemblies 36. Flight control system 22 receives sensor datafrom and sends commands to propulsion assemblies 36 to enable flightcontrol system 22 to independently control each of propulsion assemblies36 as discussed herein. In addition, aircraft 10 includes four inboardpropulsion assemblies 36 that form a two-dimensional thrust array ofsingle-axis thrust vectoring propulsion assemblies, either longitudinalthrust vectoring propulsion assemblies or lateral thrust vectoringpropulsion assemblies, preferably having the alternate thrust type ofthe outboard propulsion assemblies 36. Inboard propulsion assemblies 36each include an electronics node depicted as including controllers,sensors and one or more batteries, a single-axis gimbal operated by anactuator and a propulsion system including an electric motor and a rotorassembly. The flight control system 22 is operably associated withpropulsion assemblies 36 and is communicably linked to the electronicnodes thereof by a communications network depicted as the arrows betweenflight control system 22 and propulsion assemblies 36. Flight controlsystem 22 receives sensor data from and sends commands to propulsionassemblies 36 to enable flight control system 22 to independentlycontrol each of propulsion assemblies 36 as discussed herein. Thus, thethrust array configuration of aircraft 10 depicted in FIG. 4C includesinboard propulsion assemblies 36 having a first thrust type, single-axisthrust vectoring in one of the lateral or longitudinal direction, andoutboard propulsion assemblies 36 having a second thrust type,single-axis thrust vectoring in the other of the lateral or longitudinaldirection.

FIG. 4D depicts another embodiment of a thrust array configuration ofaircraft 10. Specifically, aircraft 10 includes four outboard propulsionassemblies 36 that form a two-dimensional thrust array of single-axisthrust vectoring propulsion assemblies, either longitudinal thrustvectoring propulsion assemblies or lateral thrust vectoring propulsionassemblies. Propulsion assemblies 36 each include an electronics nodedepicted as including controllers, sensors and one or more batteries, asingle-axis gimbal operated by an actuator and a propulsion systemincluding an electric motor and a rotor assembly. The flight controlsystem 22 is operably associated with propulsion assemblies 36 and iscommunicably linked to the electronic nodes thereof by a communicationsnetwork depicted as the arrows between flight control system 22 andpropulsion assemblies 36. Flight control system 22 receives sensor datafrom and sends commands to propulsion assemblies 36 to enable flightcontrol system 22 to independently control each of propulsion assemblies36 as discussed herein. In addition, aircraft 10 includes four inboardpropulsion assemblies 24 that form a two-dimensional thrust array of nonthrust vectoring propulsion assemblies. Propulsion assemblies 24 eachinclude an electronics node depicted as including controllers, sensorsand one or more batteries and a propulsion system including an electricmotor and a rotor assembly. The flight control system 22 is operablyassociated with propulsion assemblies 24 and is communicably linked tothe electronic nodes thereof by a communications network depicted as thearrows between flight control system 22 and propulsion assemblies 24.Flight control system 22 receives sensor data from and sends commands topropulsion assemblies 24 to enable flight control system 22 toindependently control each of propulsion assemblies 24 as discussedherein. Thus, the thrust array configuration of aircraft 10 depicted inFIG. 4D includes outboard propulsion assemblies 36 having a first thrusttype, single-axis thrust vectoring in one of the lateral or longitudinaldirection, and inboard propulsion assemblies 24 having a second thrusttype, non thrust vectoring.

Even though particular embodiments of the thrust array configuration ofaircraft 10 have been depicted and described, those having ordinaryskill in the art will recognize that the mission configurable aircraftof the present disclosure has a multitude of additional and/or alternatethrust array configurations. For example, aircraft 10 could have fouroutboard propulsion assemblies 36 that form a two-dimensional thrustarray of single-axis thrust vectoring propulsion assemblies, eitherlongitudinal thrust vectoring propulsion assemblies or lateral thrustvectoring propulsion assemblies and four inboard propulsion assemblies26 that form a two-dimensional thrust array of omnidirectional thrustvectoring propulsion assemblies. As another alternative, aircraft 10could have four outboard propulsion assemblies 24 that form atwo-dimensional thrust array of non thrust vectoring propulsionassemblies and four inboard propulsion assemblies 26 that form atwo-dimensional thrust array of omnidirectional thrust vectoringpropulsion assemblies. As still another alternative, aircraft 10 couldhave four inboard propulsion assemblies 36 that form a two-dimensionalthrust array of single-axis thrust vectoring propulsion assemblies,either longitudinal thrust vectoring propulsion assemblies or lateralthrust vectoring propulsion assemblies and four outboard propulsionassemblies 24 that form a two-dimensional thrust array of non thrustvectoring propulsion assemblies.

In addition to thrust array configurations having four inboardpropulsion assemblies and four outboard propulsion assemblies, missionconfigurable aircraft 10 may have thrust array configurations with othernumbers of propulsion assemblies. For example, as best seen in FIGS.8A-8B, aircraft 10 has been configured with four propulsion assemblies26 that form a two-dimensional distributed thrust array ofomnidirectional thrust vectoring propulsion assemblies. In theillustrated embodiment, the airframe 12 is the same airframe describedherein including wings 14, 16 each having two pylon stations and fournacelle stations. Extending generally perpendicularly between wings 14,16 are two truss structures depicted as pylons 18, 20 each of which iscoupled between two pylon stations of wings 14, 16 and preferablyforming mechanical and electrical connections therebetween. Pylons 18,20 each have a nacelle station and a payload station. Wings 14, 16 andpylons 18, 20 preferably include central passageways operable to containsystems such as flight control systems, energy sources and communicationlines that enable the flight control system to communicate with thethrust array of aircraft 10. In the illustrated embodiment, payload 30is selectively couplable between the payload stations of pylons 18, 20preferably forming a mechanical and electrical connection therebetween.

FIGS. 9A-9B, depict aircraft 10 configured with four outboard propulsionassemblies 26 that form a two-dimensional distributed thrust array ofomnidirectional thrust vectoring propulsion assemblies and two inboardpropulsion assemblies 24 that form a distributed thrust array of nonthrust vectoring propulsion assemblies. In the illustrated embodiment,the airframe 12 is the same airframe described herein including wings14, 16 each having two pylon stations and four nacelle stations.Extending generally perpendicularly between wings 14, 16 are two trussstructures depicted as pylons 18, 20 each of which is coupled betweentwo pylon stations of wings 14, 16 and preferably forming mechanical andelectrical connections therebetween. Pylons 18, 20 each have a nacellestation and a payload station. Wings 14, 16 and pylons 18, 20 preferablyinclude central passageways operable to contain systems such as flightcontrol systems, energy sources and communication lines that enable theflight control system to communicate with the thrust array of aircraft10. In the illustrated embodiment, payload 30 is selectively couplablebetween the payload stations of pylons 18, 20 preferably forming amechanical and electrical connection therebetween.

FIGS. 10A-10B, depict aircraft 10 configured with four outboardpropulsion assemblies 26 that form a two-dimensional distributed thrustarray of omnidirectional thrust vectoring propulsion assemblies and sixinboard propulsion assemblies 24 that form a two-dimensional distributedthrust array of non thrust vectoring propulsion assemblies. In theillustrated embodiment, the airframe 12 is the same airframe describedherein including wings 14, 16 each having two pylon stations and fournacelle stations. Extending generally perpendicularly between wings 14,16 are two truss structures depicted as pylons 18, 20 each of which iscoupled between two pylon stations of wings 14, 16 and preferablyforming mechanical and electrical connections therebetween. Pylons 18,20 each have a nacelle station and a payload station. Wings 14, 16 andpylons 18, 20 preferably include central passageways operable to containsystems such as flight control systems, energy sources and communicationlines that enable the flight control system to communicate with thethrust array of aircraft 10. In the illustrated embodiment, payload 30is selectively couplable between the payload stations of pylons 18, 20preferably forming a mechanical and electrical connection therebetween.

The versatility of the mission configurable aircraft of the presentdisclosure enables a single aircraft or fleet of aircraft to become amission specific suite of aircraft. For example, in a mission scenarioof picking up and delivering a payload, aircraft 10 could initially beconfigured as shown in FIGS. 8A-8B with four outboard propulsionassemblies 26 that form a two-dimensional distributed thrust array ofomnidirectional thrust vectoring propulsion assemblies located on theoutboard nacelle stations of aircraft 10. This initial thrust arrayconfiguration provides aircraft 10 with the necessary thrust capacityand vehicle control to fly from a storage location such as an aircrafthub or hanger or a field location such as within a military theater tothe location of the payload to be picked up, without the weight penaltyof carrying the inboard propulsion assemblies and the accompanying lossof efficiency. Upon reaching the payload location, aircraft 10 could bereconfigured to the configuration as shown in FIGS. 10A-10B keeping thefour outboard propulsion assemblies 26 and adding six inboard propulsionassemblies 24 that form a two-dimensional distributed thrust array ofnon thrust vectoring propulsion assemblies located on the inboardnacelle stations of aircraft 10. This thrust array configurationprovides aircraft 10 with the added thrust capacity to lift andtransport a heavy payload 30 to a delivery location. After delivery ofpayload 30, aircraft 10 could again be reconfigured to the configurationshown in FIGS. 8A-8B, FIGS. 9A-9B, FIGS. 1A-1G, any of FIGS. 4A-4D orother desired configuration depending upon the parameters of the nextmission.

In certain implementations, the mission configurable aircraft of thepresent disclosure may be part of a man portable aircraft system that iseasily transportable and operable for rapid in-situ assembly. Such a manportable aircraft system 100 is depicted in FIGS. 11A-11D of thedrawings. Man portable aircraft system 100 includes a container 102formed from a base 102 a and a cover 102 b that may be secured togetherwith hinges, latches, locks or other suitable connections. Cover 102 band/or base 102 a may include handles, straps or other means to enablecontainer 102 with aircraft 10 therein to be easily moved or carried. Asused herein, the term “man portable” means capable of being carried byone man. As a military term in land warfare, “man portable” meanscapable of being carried by one man over a long distance without seriousdegradation to the performance of normal duties. The term “man portable”may be used to qualify items, for example, a man portable item is onedesigned to be carried as an integral part of individual, crew-served orteam equipment of a dismounted soldier in conjunction with assignedduties and/or an item with an upper weight limit of approximately 31pounds.

In the illustrated embodiment, container 102 has an insert 104 disposedwithin base 102 a having precut locations that are designed to receivethe various component parts of aircraft 10 therein while aircraft 10 isin a disassembled state. Aircraft 10 of man portable aircraft system 100is preferably operable to transition between thrust-borne lift in a VTOLorientation and wing-borne lift in a biplane orientation, as discussedherein. In the illustrated embodiment, man portable aircraft system 100includes wing 14 that has first and second pylon stations, first andsecond inboard nacelle stations and first and second outboard nacellestations. Man portable aircraft system 100 also includes wing 16 havingfirst and second pylon stations, first and second inboard nacellestations and first and second outboard nacelle stations. Man portableaircraft system 100 further includes pylon 18 that is couplable betweenthe first pylon stations of wings 14, 16 and pylon 20 that is couplablebetween the second pylon stations of wings 14, 16. Pylons 18, 20 eachinclude a payload station and an inboard nacelle station. Whenassembled, wings 14, 16 and pylons 18, 20 form the airframe of aircraft10. Man portable aircraft system 100 includes six inboard propulsionassemblies 24 which represent the maximum number of inboard propulsionassemblies that may be coupled to the inboard nacelle stations of wings14, 16 and/or pylons 18, 20. Man portable aircraft system 100 alsoincludes four outboard propulsion assemblies 26 which represent themaximum number of outboard propulsion assemblies that may be coupled tothe outboard nacelle stations of wings 14, 16. In the illustratedembodiment, a flight control system 20 a is disposed within pylon 20 andis operable to independently control each of the propulsion assembliesonce aircraft 10 is in an assembled state. One or more batteries (notshown) may also be located in pylon 20, within other airframe membersand preferably within each propulsion assembly 24, 26. Man portableaircraft system 100 includes a payload 30 that is operable to be coupledbetween the payload stations of pylons 18, 20. Payload 30 may carry,include or be integral with a variety of modules such as a packagedelivery module, an air reconnaissance module, a light detection andranging module, a camera module, an optical targeting module, a lasermodule, a sensors module, an air-to-ground weapons module, an air-to-airweapons module, a communications module and/or a cargo hook module orthe like depending upon the mission being perform by aircraft 10. Thus,in certain configurations, aircraft 10 may be operable as a man portableobservation platform.

Man portable aircraft system 100 includes a computing system 108,depicted as a tablet computer that is operable as a ground controlstation for aircraft 10. Computing system 108 preferably includesnon-transitory computer readable storage media including one or moresets of computer instructions or applications that are executable by oneor more processors for configuring, programming and/or remotelycontrolling aircraft 10. Computing system 108 may be one or moregeneral-purpose computers, special purpose computers or other machineswith memory and processing capability. Computing system 108 may includeone or more memory storage modules including, but is not limited to,internal storage memory such as random access memory, non-volatilememory such as read only memory, removable memory such as magneticstorage memory, optical storage, solid-state storage memory or othersuitable memory storage entity. Computing system 108 may be amicroprocessor-based system operable to execute program code in the formof machine-executable instructions. In addition, computing system 108may be selectively connectable to other computer systems via aproprietary encrypted network, a public encrypted network, the Internetor other suitable communication network that may include both wired andwireless connections.

In the illustrated man portable aircraft system 100, computing system108 is operable for automated configuration of a mission specificaircraft as described with reference to FIG. 12. In process 150,computing system 108 is configured to receive mission parametersincluding flight parameters and payload parameters, as indicated inblock 152. The flight parameters may include time requirements, flightspeed requirements, elevation requirements, range requirements,endurance requirements, environmental conditions and the like that maybe manually input into computing system 108 or received as a digitalflight plan from another computing entity over a wired and/or wirelesscommunication channel. The payload parameters may include payload weightrequirements, payload functionality requirements, payload coupling anddecoupling requirements, payload operational requirements and the like.In block 154, based upon the mission parameters, computing system 108configures the airframe including selecting a flight control system,selecting the wings and selecting the pylons. While the illustrated manportable aircraft system 100 included only one set of wings, pylons anda flight control system, other man portable aircraft systems may includeadditional or different airframe components. For example, other manportable aircraft systems may have wings and pylons of different sizes,wings and pylons made from other materials, wings and pylons havingother numbers of or locations for inboard and/or outboard propulsionassemblies, flight control systems having different capabilities and thelike. Accordingly, computing system 108 is operable for mission specificaircraft configuration using a wide variety of different airframecomponents. In the illustrated example of man portable aircraft system100, computing system 108 is operable to select wing 14 having first andsecond pylon stations, first and second inboard nacelle stations andfirst and second outboard nacelle stations, wing 16 having first andsecond pylon stations, first and second inboard nacelle stations andfirst and second outboard nacelle stations, pylon 18 having a payloadstation, an inboard nacelle station and couplable between the firstpylon stations of wings 14, 16 and pylon 20 having a payload station, aninboard nacelle station and couplable between the second pylon stationsof wings 14, 16.

In block 156, computing system 108 is operable to determine the thrustrequirements for aircraft 10 based upon the mission parameters. Thisprocess will identify a thrust array capable of the total and/or maximumthrust requirements of aircraft 10 based on upon various expectedoperating conditions including, for example, the thrust requirementduring VTOL operations, the thrust requirement for stable hover in alevel flight attitude, the thrust requirement for stable hover in aninclined flight attitude, the thrust requirement for attitude stabilityduring translation and/or other high or unique thrust demand conditions.This process may also identify a thrust array capable of high efficiencyfor high endurance missions. In block 158, computing system 108 isoperable to configure a two-dimensional distributed thrust array basedupon the thrust requirements. This process includes selecting thenumber, the type and the mounting locations for the propulsionassemblies. As an example, this process may include selecting the numberand type of batteries to be contained within the selected propulsionassemblies. As another example, this process may include selectingvarious rotor blades for the selected propulsion assemblies such asselecting the number of rotor blades, the rotor assembly diameter, therotor blade twist, the rotor blade chord distribution and the like. Asdiscussed herein, aircraft 10 is a mission configurable aircraft thatmay be operated with various thrust array configurations such as withonly outboard propulsion assembles as depicted in FIGS. 8A-8B, withoutboard propulsion assembles and pylon mounted inboard propulsionassemblies as depicted in FIGS. 9A-9B, with outboard propulsionassembles and wing mounted inboard propulsion assemblies as depicted inFIGS. 1A-2I, or with outboard propulsion assembles, wing mounted inboardpropulsion assemblies and pylon mounted inboard propulsion assemblies asdepicted in FIGS. 10A-10B, as examples.

In the illustrated example of man portable aircraft system 100,computing system 108 is operable to select a plurality of inboardpropulsion assemblies having a first thrust type operable for couplingto the first and second inboard nacelle stations of wings 14, 16, asindicated in block 160. In addition, computing system 108 is operable toselect a plurality of outboard propulsion assemblies having a secondthrust type operable for coupling to the first and second outboardnacelle stations of wings 14, 16 with the first thrust type beingdifferent from the second thrust type, as indicated in block 162. Asexamples, based upon the thrust requirements, computing system 108 mayselect outboard propulsion assemblies that are thrust vectoringpropulsion assemblies and inboard propulsion assemblies that are nonthrust vectoring propulsion assemblies. Computing system 108 may selectoutboard propulsion assemblies that are unidirectional thrust vectoringpropulsion assemblies and inboard propulsion assemblies that are nonthrust vectoring propulsion assemblies. Computing system 108 may selectoutboard propulsion assemblies that are omnidirectional thrust vectoringpropulsion assemblies and inboard propulsion assemblies that are nonthrust vectoring propulsion assemblies. Computing system 108 may selectoutboard propulsion assemblies that are omnidirectional thrust vectoringpropulsion assemblies and inboard propulsion assemblies that areunidirectional thrust vectoring propulsion assemblies. Computing system108 may select inboard propulsion assemblies that are longitudinalthrust vectoring propulsion assemblies and outboard propulsionassemblies that are lateral thrust vectoring propulsion assemblies.Computing system 108 may select outboard propulsion assemblies that arelongitudinal thrust vectoring propulsion assemblies and inboardpropulsion assemblies that are lateral thrust vectoring propulsionassemblies.

Referring additional to FIG. 13, computing system 108 not only includesthe configuring application 170, but also includes a programmingapplication 172 and a remote control application 174. Programmingapplication 172 enables a user to provide a flight plan and missioninformation to aircraft 10 such that flight control system 22 may engagein autonomous control over aircraft 10. For example, programmingapplication 172 may communicate with flight control system 22 over awired or wireless communication channel 176 to provide a flight planincluding, for example, a staring point, a trail of waypoints and anending point such that flight control system 22 may use waypointnavigation during the mission. In addition, programming application 172may provide one or more tasks to flight control system 22 for aircraft10 to accomplish during the mission. Following programming, aircraft 10may operate autonomously responsive to commands generated by flightcontrol system 22. In the illustrated embodiment, flight control system22 includes a command module 178 and a monitoring module 180. It is tobe understood by those skilled in the art that these and other modulesexecuted by flight control system 22 may be implemented in a variety offorms including hardware, software, firmware, special purpose processorsand combinations thereof.

During flight operations, command module 178 sends commands to inboardpropulsion assemblies 24 and outboard propulsion assemblies 26 toindividually and independently control and operate each propulsionassembly. For example, flight control system 22 is operable toindividually and independently control the operating speed, the thrustvector and the aerosurface position of the propulsion assembly. Inaddition, command module 178 may send commands to payload module 30 suchthat payload module 30 may accomplish the intended mission. For example,upon reaching an operational location, command module 178 may commandpayload module 30 to release a package, engage in a surveillanceoperation, optically mark a target, launch an air-to-ground orair-to-air weapon, deploy a cargo hook or perform another payload modulefunction. Also during flight operation, monitoring module 180 receivesfeedback from the various elements within inboard propulsion assemblies24, outboard propulsion assemblies 26 and payload module 30 such asinformation from sensors, controllers, actuators and the like. Thisfeedback is processed by monitoring module 180 to supply correction dataand other information to command module 178. Aircraft 10 may utilizeadditional sensor systems such as altitude sensors, attitude sensors,speed sensors, environmental sensors, fuel supply sensors, temperaturesensors and the like that also provide information to monitoring module180 to further enhance autonomous control capabilities. Some or all ofthe autonomous control capability of flight control system 22 can beaugmented or supplanted by remote control application 174 of computingsystem 108. Computing system 108 may communicate with flight controlsystem 22 in real-time over communication link 176. Computing system 108preferably includes one or more display devices 182 configured todisplay information relating to or obtained by one or more aircraft ofthe present disclosure. Computing system 108 may also include audiooutput and input devices such as a microphone, speakers and/or an audioport allowing an operator to communicate with, for example, other remotestation operators. Display device 182 may also serve as a remote inputdevice 184 in touch screen display implementation, however, other remoteinput devices, such as a keyboard or joysticks, may alternatively beused to allow an operator to provide control commands to aircraft 10.Accordingly, aircraft 10 of man portable aircraft system 100 may beoperated responsive to remote flight control, autonomous flight controland combinations thereof

Returning again to the automated configuration functionality ofcomputing system 108, once the design parameters of aircraft 10 havebeen determined by configuring application 170, man portable aircraftsystem 100 is operable for rapid in-situ assembly of aircraft 10.Specifically, the connections between the wings, the pylons, thepropulsion assemblies and the payload of man portable aircraft system100 are each operable for rapid in-situ assembly through the use of highspeed fastening elements. For example, referring additionally to FIGS.14A-14C of the drawings, the structural and electrical connectionsbetween an inboard nacelle station of a wing and an inboard propulsionassembly will now be described. In the illustrated embodiment, a sectionof wing 16 include inboard nacelle station 16 e which is oppositelydisposed from pylon station 16 a. Inboard nacelle station 16 e has arapid connection interface that includes a pair of upper mechanicalconnections depicted as cams 16 g, 16 h, the outer slot portion of eachbeing visible in the figures. Inboard nacelle station 16 e includes alower mechanical connection depicted as spring 16 i. Disposed betweenupper mechanical connections 16 g, 16 h and lower mechanical connection16 i is a central mechanical connection including an electricalconnection depicted as a female mating profile with a plurality ofelectrical pins 16 j, such as spring biased pins. In the illustratedembodiment, inboard propulsion assembly 24 including a rapid connectioninterface 24 h having a pair of upper mechanical connections depicted ashooks 24 i, 24 j and a lower mechanical connection depicted as a slottedfastener 24 k. Disposed between upper mechanical connections 24 i, 24 jand lower mechanical connection 24 k is a central mechanical connectionincluding an electrical connection depicted as a male mating profilewith a plurality of electrical sockets 241.

In operation, inboard nacelle station 16 e and inboard propulsionassembly 24 may be coupled and decoupled with simple operations.Specifically, to coupled inboard propulsion assembly 24 with inboardnacelle station 16 e, the distal ends of hooks 24 i, 24 j are insertedinto the outer slots of cams 16 g, 16 h with inboard propulsion assembly24 tilted relative to inboard nacelle station 16 e at an angle betweenabout 30 degrees and about 60 degrees. Once hooks 24 i, 24 j areinserted into cams 16 g, 16 h, inboard propulsion assembly 24 is rotatedrelative to inboard nacelle station 16 e about cams 16 g, 16 h to reducethe angle therebetween, such that hooks 24 i, 24 j further penetrateinto inboard nacelle station 16 e providing a self location operationfor the other mechanical and electrical connections. Specifically, asthe angle between inboard propulsion assembly 24 and inboard nacellestation 16 e is reduced, the male mating profile enters the femalemating profile and pins 16 j sequentially enter sockets 241 forming amulti-channel parallel interface. Depending upon the number of pin andsockets as well as the desired communication protocol being establishedtherebetween, this electrical connection may provide singlecommunication channels, redundant communication channels or triplyredundant communication channels for the transfer of control commands,low power current, high power current and/or other signals betweeninboard propulsion assembly 24 and inboard nacelle station 16 e toenable, for example, communication between flight control system 22 andcomponents within inboard propulsion assembly 24 such as battery 24 b,electronic speed controller 24 c, electronics node 24 d, sensors and/orother electronic equipment, as discussed herein.

As the angle between inboard propulsion assembly 24 and inboard nacellestation 16 e is further reduced, a lower mechanical connection betweeninboard propulsion assembly 24 and inboard nacelle station 16 e isestablished with slotted fastener 24 k and spring 16 i. Once spring 16 ienters the channel of slotted fastener 24 k, a simple manual orautomated quarter turn rotation of slotted fastener 24 k securelycompletes the mechanical and electrical connection of inboard propulsionassembly 24 with inboard nacelle station 16 e. In a similar manner, thevarious connections may be made between pylons 18, 20 and pylon stations14 a, 14 b, 16 a, 16 b, outboard propulsion assemblies 26 and outboardnacelle stations 14 c, 14 d, 16 c, 16 d, payload 30 and payload stations18 b, 20 b as well as the other inboard propulsion assemblies 24 andinboard nacelle stations 14 e, 14 f, 16 f, 18 a, 20 a, in accordancewith the desired configuration of aircraft 10.

Disassembly of aircraft 10 is achieved by reversing the assemblyprocess. Referring again to FIGS. 14A-14C, from the assembled state, aquarter turn rotation of slotted fastener 24 k enables separation ofslotted fastener 24 k from spring 16 i. Thereafter, inboard propulsionassembly 24 is rotated relative to inboard nacelle station 16 e aboutcams 16 g, 16 h to increase the angle therebetween. As the angle betweeninboard propulsion assembly 24 and inboard nacelle station 16 e isincreased, the electrical connection between inboard propulsion assembly24 and inboard nacelle station 16 e is released as pins 16 jsequentially separate from sockets 241 and the male mating profileseparates from the female mating profile. As the angle between inboardpropulsion assembly 24 and inboard nacelle station 16 e is furtherincreased, hooks 24 i, 24 j are released from cams 16 g, 16 completingthe mechanical and electrical decoupling of inboard propulsion assembly24 from inboard nacelle station 16 e. In a similar manner, theconnections between pylons 18, 20 and pylon stations 14 a, 14 b, 16 a,16 b, outboard propulsion assemblies 26 and outboard nacelle stations 14c, 14 d, 16 c, 16 d, payload 30 and payload stations 18 b, 20 b as wellas the other inboard propulsion assemblies 24 and inboard nacellestations 14 e, 14 f, 16 f, 18 a, 20 a may be decoupled.

Referring to FIGS. 15A-15B of the drawings, an alternate embodiment ofthe structural and electrical connections between components of aircraft10 will now be described. In the illustrated embodiment, a rapidconnection interface 200 includes a pair of upper mechanical connectionsdepicted as cams 202, 204 and a lower mechanical connection depicted asa female snap element 206. Disposed between upper mechanical connections202, 204 and lower mechanical connection 206 is a central mechanicalconnection including an electrical connection depicted as a femalemating profile and a plurality of pins 208. Rapid connection interface200 may represent the connection interface of an inboard or outboardnacelle station, a pylon station and/or a payload station. In theillustrated embodiment, a rapid connection interface 210 includes a pairof upper mechanical connections depicted as hooks 212, 214 and a lowermechanical connection depicted as a male snap element 216. Disposedbetween upper mechanical connections 212, 214 and lower mechanicalconnection 216 is a central mechanical connection including anelectrical connection depicted as a male mating profile and a pluralityof sockets 218. Rapid connection interface 210 may represent theconnection interface of an inboard or outboard propulsion assembly, apylon and/or a payload. The connection of rapid connection interface 200with rapid connection interface 210 is substantially similarly to theconnection of inboard nacelle station 16 e with rapid connectioninterface 24 h described above with the exception that instead of usinga quarter turn operation to securely complete the mechanical andelectrical connection, a snapping operation is used to securely completethe mechanical and electrical connection. Likewise, the disassembly ofrapid connection interface 200 from rapid connection interface 210 issubstantially similarly to the disassembly of inboard nacelle station 16e and rapid connection interface 24 h described above with the exceptionthat instead of using a quarter turn operation to release the lowermechanical connection, an unsnapping operation is used to release thelower mechanical connection.

Referring to FIGS. 16A-16B of the drawings, another alternate embodimentof the structural and electrical connections between components ofaircraft 10 will now be described. In the illustrated embodiment, arapid connection interface 220 includes a pair of upper mechanicalconnections depicted as cams 222, 224 and a lower connection depicted asa magnetic element 226 such as a permanent magnet, a switchable magnetor an electromagnet. Disposed between upper mechanical connections 222,224 and lower connection 226 is a central mechanical connectionincluding an electrical connection depicted as a female mating profileand a plurality of pins 228. Rapid connection interface 220 mayrepresent the connection interface of an inboard or outboard nacellestation, a pylon station and/or a payload station. In the illustratedembodiment, a rapid connection interface 230 includes a pair of uppermechanical connections depicted as hooks 232, 234 and a lower connectiondepicted as a magnetic element 236 such as a permanent magnet, aswitchable magnet or an electromagnet. Disposed between upper mechanicalconnections 232, 234 and lower connection 236 is a central mechanicalconnection including an electrical connection depicted as a male matingprofile and a plurality of sockets 238. Rapid connection interface 230may represent the connection interface of an inboard or outboardpropulsion assembly, a pylon and/or a payload. The connection of rapidconnection interface 220 with rapid connection interface 230 issubstantially similarly to the connection of inboard nacelle station 16e with rapid connection interface 24 h described above with theexception that instead of using a quarter turn operation to securelycomplete the mechanical and electrical connection, magnetic attractionis used to securely complete the mechanical and electrical connectionby, for example, establishing an electrical current to energize anelectromagnet. Likewise, the disassembly of rapid connection interface220 with rapid connection interface 230 is substantially similarly tothe disassembly of inboard nacelle station 16 e from rapid connectioninterface 24 h described above with the exception that instead of usinga quarter turn operation to release the lower mechanical connection, amechanical force or discontinuing the electrical current is used torelease the lower connection.

Referring to FIGS. 17A-17B of the drawings, a further alternateembodiment of the structural and electrical connections betweencomponents of aircraft 10 will now be described. This embodiment isparticularly useful for payload coupling when remote releasecapabilities are desired. In the illustrated embodiment, a rapidconnection interface 240 includes a pair of upper connections depictedas electromagnets 242, 244 and a lower connection depicted as anelectromagnet 246. Disposed between upper connections 242, 244 and lowerconnection 246 is an electrical connection depicted as a plurality ofpins 248. Rapid connection interface 240 may represent the connectioninterface of a payload station. In the illustrated embodiment, a rapidconnection interface 250 includes a pair of upper connections depictedas magnets 252, 254 and a lower connection depicted as a magnet 256.Disposed between upper connections 252, 254 and lower connection 256 isan electrical connection depicted as a plurality of sockets 258. Rapidconnection interface 250 may represent the connection interface of apayload. The connection of rapid connection interface 240 with rapidconnection interface 250 is achieved by aligning upper connections 242,244, lower connection 246 and electrical connections 248 with upperconnections 252, 254, lower connection 256 and electrical connections258 then engaging a current to create the desired magnetic attraction.In the case of the remotely releasable payload embodiment, when aircraft10 has transported payload 30 to a desired location, flight controlsystem 22, either autonomously or responsive to commands send fromcomputing system 108, may disengage the current to electromagnets 242,244, 246 which ends the magnetic attraction to magnets 252, 254, 256thus releasing payload 30 from airframe 12 either during flight or afterlanding aircraft 10.

Referring to FIGS. 18A-18D of the drawings, certain unique operations ofaircraft 10 will now be described. As discussed herein, aircraft 10 isoperable to transition between thrust-borne lift in a VTOL orientationand wing-borne lift in a biplane orientation. In addition, responsive toflight control system 22 independently controlling each propulsionassembly of aircraft 10 including speed control, thrust vectoring and/oraerosurface maneuvers, aircraft 10 is operable to maintain hoverstability in level flight attitudes and inclined flight attitudes whilealso having pitch, roll, yaw and translation authority. In theillustrated embodiment, aircraft 10 has been configured with atwo-dimensional distributed thrust array of outboard propulsionassembles 26, such as aircraft 10 depicted in FIGS. 8A-8B. Aircraft 10has a longitudinal axis 10 a and lateral axis 10 b which are eachlocated in the horizontal plane H, normal to the local vertical in theearth's reference frame, when aircraft 10 has a level flight attitude inhover (see FIG. 2B). Having hover stability in a level flight attitudeis an important characteristic achieved by many VTOL aircraft. Withaircraft 10, such hover stability in a level flight attitude is achievedand/or maintained using the various flight attitude controls asdiscussed herein. Aircraft 10, however, is also operable to achieveand/or maintain hover stability in inclined flight attitudes using thevarious flight attitude controls including speed control, thrustvectoring, aerosurface maneuvers and combinations thereof of thepropulsion assemblies. For example, aircraft 10 has in a nonzero pitchdown flight attitude in FIG. 18A and a nonzero pitch up flight attitudein FIG. 18B. Angle P represents the pitch angle relative to thehorizontal plane H that may be up to about five degrees, between aboutfive degrees and about fifteen degrees, between about fifteen degreesand about twenty-five degrees, between about twenty-five degrees andabout thirty-five degrees or other desired angle. For example, onceaircraft 10 has transitioned from hover in a level flight attitude tohover in a nonzero pitch flight attitude, aircraft 10 may maintain hoverstability in the nonzero pitch flight attitude using collective thrustvectoring of propulsion assemblies 26, as illustrated in FIGS. 18A-18B,wherein each of the rotor assemblies is rotating in a planesubstantially parallel to the horizontal plane H. Depending upon themagnitude of angle P and the maximum thrust vector angle of propulsionassemblies 26, the collective thrust vectoring flight attitude controlmay be augmented with differential speed control and/or aerosurfacemaneuvers of propulsion assemblies 26. The ability to maintain hoverstability in a nonzero pitch flight attitude may be particularly usefulduring missions requiring orientation of payload 30 relative to astationary or moving target on the ground or in the air such as duringmissions using the light detection and ranging module, the cameramodule, the optical targeting module, the laser module, theair-to-ground weapons module or the air-to-air weapons module.

Aircraft 10 has in a nonzero roll right flight attitude in FIG. 18C anda nonzero roll left flight attitude in FIG. 18D. Angle R represents theroll angle relative to the horizontal plane H that may be up to aboutfive degrees, between about five degrees and about fifteen degrees,between about fifteen degrees and about twenty-five degrees, betweenabout twenty-five degrees and about thirty-five degrees or other desiredangle. For example, once aircraft 10 has transitioned from hover in alevel flight attitude to hover in a nonzero roll flight attitude,aircraft 10 may maintain hover stability in the nonzero roll flightattitude using collective thrust vectoring of propulsion assemblies 26as illustrated in FIGS. 18C-18D, wherein each of the rotor assemblies isrotating in plane substantially parallel to the horizontal plane H.Depending upon the magnitude of angle R and the maximum thrust vectorangle of propulsion assemblies 26, the collective thrust vectoringflight attitude control may be augmented with differential speed controland/or aerosurface maneuvers of propulsion assemblies 26. The ability tomaintain hover stability in a nonzero roll flight attitude may beparticularly useful during missions using the package delivery module,the cargo hook module or missions requiring vertical takeoffs andlandings on unlevel surfaces and/or autonomous or self-docking ofaircraft 10.

While FIGS. 18A-18B have described and depicted aircraft 10 maintaininghover stability in a nonzero pitch flight attitude and FIGS. 18C-18Dhave described and depicted aircraft 10 maintaining hover stability in anonzero roll flight attitude, it should be understood by those havingordinary skill in the art that aircraft 10 is also operable to maintainhover stability when aircraft 10 has a combination of a nonzero pitchflight attitude and a nonzero roll flight attitude using the variousflight attitude controls of aircraft 10 including speed control, thrustvectoring, aerosurface maneuvers and combinations thereof of thepropulsion assemblies. To maintain hover stability in any inclinedflight attitude, the propulsion system of aircraft 10 should preferablybe formed as a two-dimensional distributed array of omnidirectionalthrust vectoring propulsion assemblies. It is noted, however, thatselected hover stability in a single inclined orientation could beachieved with collective thrust vectoring of a two-dimensionaldistributed array of unidirectional thrust vectoring propulsionassemblies. For example, maintaining hover stability in the nonzeropitch flight attitude may be achieved using collective thrust vectoringof propulsion assemblies having longitudinal thrust vectoringcapabilities. Likewise, maintaining hover stability in the nonzero rollflight attitude may be achieved using collective thrust vectoring ofpropulsion assemblies having lateral thrust vectoring capabilities.

FIG. 19A-19B depict additional capabilities of aircraft 10 that areachievable through flight control system 22 independently controllingeach propulsion assembly of aircraft 10 including speed control, thrustvectoring, aerosurface maneuvers and combinations thereof. Aircraft 10is depicted with payload 30 having an aerial imaging module 260 such asa light detection and ranging module, a camera module, an X-ray moduleor the like. As illustrated, aerial imaging module 260 is orientatedtoward a focal point 262 of a stationary object 264 on the ground suchas a military target or a structure being inspected. As represented byarrow 266, flight control system 22 is operable to maintain theorientation of aerial imaging module 260 toward focal point 262 whenaircraft 10 is translating in a level flight attitude, such as moving inthe depicted fore-aft direction, moving in the lateral direction ormoving in any diagonal direction therebetween. This translation isaccomplished responsive to controlling the speed, the thrust vectorand/or the aerosurface position of each of the propulsion assemblies.

Similarly, as represented by arrows 268, 270, flight control system 22is operable to maintain the orientation of aerial imaging module 260toward focal point 262 when aircraft 10 is changing altitude bysimultaneously adjusting the flight attitude of aircraft 10. Thesealtitude and attitude changes are accomplished responsive to controllingthe speed, the thrust vector and/or the aerosurface position of each ofthe propulsion assemblies. For example, as aircraft 10 increasesaltitude from the lower right position to the middle position alongarrow 268, aircraft 10 transitions from a level flight attitude to apitch down flight attitude with an incline or pitch angle P of betweenabout five degrees and about fifteen degrees. As aircraft 10 furtherincreases altitude from the middle position to the upper right positionalong arrow 270, aircraft 10 transitions from a pitch down flightattitude with an incline or pitch angle P of between about five degreesand about fifteen degrees to a pitch down flight attitude with anincline or pitch angle P of between about fifteen degrees and abouttwenty-five degrees.

As represented by arrows 272, 274 in FIG. 19B, flight control system 22is operable to maintain the orientation of aerial imaging module 260toward focal point 262 when aircraft 10 is translating in an inclinedflight attitude, such as moving in the fore-aft direction, moving in thedepicted lateral direction or moving in any diagonal directiontherebetween. This translation is accomplished responsive to controllingthe speed, the thrust vector and/or the aerosurface position of each ofthe propulsion assemblies. In one example, aircraft 10 is operable totravel in circles around stationary object 264 while maintaining theorientation of aerial imaging module 260 toward focal point 262 toengage in, for example, phased array aerial imaging and/or threedimensional aerial imaging of ground object 264.

Referring next to FIGS. 20A-20D, an advantageous use of aircraft 10during external load operations is depicted. As discussed herein,aircraft 10 is operable to transition between thrust-borne lift in aVTOL orientation and wing-borne lift in a biplane orientation. Inaddition, in the VTOL orientation, aircraft 10 is operable to maintainhover stability while translating in a level flight attitude or aninclined flight attitude using the various flight attitude controlsdiscussed herein. These unique capabilities of aircraft 10 enableaircraft 10 to lift, carry and transport cargo and/or equipmentexternally as a sling load. For example, aircraft 10 may engage inexternal load operations for military campaigns including ship-to-shoremovement of equipment during amphibious operations, movement of suppliesover a battlefield, vertical replenishment of ships, firepoweremplacement and the like without putting pilots at risk. Aircraft 10provides external load transportation advantages including the rapidmovement of heavy or outsized equipment, efficient delivery of emergencysupplies directly to the user, the ability to bypass surface obstaclesas well as the use of multiple flight routes and/or landing sites,thereby providing improved movement flexibility to accomplish a mission.

In FIG. 20A, aircraft 10 is engaged in aerial crane operations.Specifically, aircraft 10 includes payload 30 having a cargo hook module280. In the illustrated embodiment, cargo hook module 280 includes afixed cargo hook attached to a lower portion of payload 30 when aircraft10 is in the VTOL orientation. The cargo hook is operable to receive andsuspend equipment underneath aircraft 10. In the illustrated embodiment,a cargo net 282 is being used to support supplies and/or equipmentdisposed therein. The cargo hook may be opened manually and/orelectrically by the ground crew during hookup and release operationswhile aircraft 10 is on the ground or during flight by attaching orremoving, for example, a cargo net apex fitting ring from the cargohook. During flight, a spring-loaded keeper prevents the fitting ringfrom slipping off the load beam of the cargo hook. In FIG. 20A, aircraft10 is engaging in thrust-borne lift in the VTOL orientation and isascending, as indicated by arrow 284, with the external load disposedwithin cargo net 282 and supported by cargo hook module 280. In FIG.20B, aircraft 10 has transitioned to wing-borne lift in the biplaneorientation and is engaged in forward flight, as indicated by arrow 286.Depending upon the weight of the external load, aircraft 10 may be in alow thrust to weight configuration and may use a low thrust to weighttransition procedure for the thrust-borne lift to wing-borne lifttransition, as discussed herein. Upon arrival at the destination,aircraft 10 may transition back to the VTOL orientation and lower theexternal load such that ground crew may manually and/or electricallyopen the cargo hook to release the external load while aircraft 10remains in the air or after aircraft 10 has landed.

FIG. 20C, depicts an alternate embodiment of aircraft 10 having apayload 30 including a cargo hook module 288. In the illustratedembodiment, cargo hook module 288 includes a cargo hoisting deviceoperable to raise and lower an external load while aircraft 10 remainsin a stable hover. Cargo hook module 288 includes a retractable hoistingcable 290 that is supported by a cargo hook winch system 292 for raisingand lowering the cargo hook, as indicated by arrow 294. FIG. 20D,depicts another alternate embodiment of aircraft 10 having a payload 30including a cargo hook module 296. In the illustrated embodiment, cargohook module 296 includes a remote or free-swinging cargo hook on a fixedlength sling leg assembly cable 298 that is operable to suspend thecargo hook a desired distance from the bottom of aircraft 10.

Referring additionally to FIGS. 21A-21E and 22A-22E, multiple VTOL tobiplane transition procedures selected based upon the thrust to weightconfiguration of aircraft 10 will now be described. As discussed herein,aircraft 10 is a mission configurable aircraft that is operable totransition between thrust-borne lift in a VTOL orientation andwing-borne lift in a biplane orientation. As aircraft 10 is missionconfigurable, the particular thrust array that is coupled to aparticular airframe may vary depending upon factors including flightparameters such as time requirements, flight speed requirements,elevation requirements, range requirements, endurance requirements,environmental conditions and the like as well as payload parameters suchas payload weight requirements, payload functionality requirements,payload coupling and decoupling requirements, payload operationalrequirements, external loads requirements and the like. During certainportions of a mission, such as after picking up a payload or an externalload, aircraft 10 may have a low thrust to weight configuration with athrust to weight ratio below a first predetermined threshold, whileduring other portions of a mission, such as after delivery of a payloador releasing the external load, aircraft 10 may have a high thrust toweight configuration with a thrust to weight ratio above a secondpredetermined threshold. For example, the predetermined threshold forthe low thrust to weight configuration of aircraft 10 may be about 1.4or may be stated as between about 1.1 and about 1.4. The predeterminedthreshold for the high thrust to weight configuration of aircraft 10 maybe about 1.7.

As illustrated in FIGS. 21A-21E, aircraft 10 is in a low thrust toweight configuration and thus preforms a low thrust to weight transitionprocedure. In the illustrated embodiment, aircraft 10 includes atwo-dimensional distributed thrust array of outboard propulsionassemblies 26 coupled to the outboard nacelle stations of the wings,such as the embodiment depicted in FIGS. 8A-8B. Even through aparticular aircraft is depicted in FIGS. 21A-21E, it should beunderstood by those having ordinary skill in the art that any of theaircraft of the present disclosure having omnidirectional orlongitudinal thrust vectoring propulsion assemblies could also preformthe low thrust to weight transition procedure. In this procedure, theinitial step involves engaging in a stable hover at a substantiallylevel flight attitude, as illustrated in FIG. 21A. The next stepinvolves establishing a pitch down flight attitude while maintaining astable hover, as illustrated in FIG. 21B. This step is accomplishedthrough the use of the flight attitude controls including rotor speed,thrust vector, aerosurface position and combinations thereof of one ormore of the propulsion assemblies 26. For example, using differentialspeed control the rotor assemblies 26 j of the forward propulsionassemblies relative to the aft propulsion assemblies in combination withcollective thrust vectoring, the level flight attitude is transitionedto the desired pitch down flight attitude. For example, the pitch downflight attitude may be between about 10 degrees and about 20 degreesrelative to the horizontal. Alternatively, the pitch down flightattitude may be between about 20 degrees and about 30 degrees relativeto the horizontal. The angle of the thrust vectors should substantiallymatch the pitch down angle relative to the horizontal in order tomaintain the stable hover. Optionally, collective tilting of theaerosurfaces 26 k may be use such that air blowing thereon generates apitch down moment for aircraft 10 to urge aircraft 10 in the pitch downdirection, as illustrated in FIG. 21B.

The next step involves initiating forward flight, as illustrated in FIG.21C. Beginning from the stable hover condition, collective increase ordecrease in rotor speed will result in an increase or decease inaltitude if desired. Collective reduction of the thrust vector anglescauses the rotors assemblies 26 j to tilt forward from the horizontalwhich in turn changes the direction of the thrust vectors to include notonly down components but also aft components. The aft thrust vectorcomponents initiate the forward movement of aircraft 10. As the airspeedincreases, the thrust vector angles are collective reduced whilesimultaneously increasing the pitch down attitude of aircraft 10 untilthe thrust vectors and the wings are substantially horizontal, as seenin the progression of FIGS. 21C-21E. By reducing the angle of attack ofthe wings in pitch down configuration prior to initiating forwardflight, wing-borne lift can be generated at a lower forward airspeedthus enabling the low thrust to weight transitions from VTOL orientationto biplane orientation of aircraft 10.

As illustrated in FIGS. 22A-22E, aircraft 10 is in a high thrust toweight configuration and thus preforms a high thrust to weighttransition procedure. In this procedure, the initial step may involveengaging in a stable hover at a substantially level flight attitude, asillustrated in FIG. 22A. From this condition, collective increase ordecrease in rotor speed will result in an increase or decease inaltitude if desired. The next step involves engaging in collectivethrust vectoring of propulsion assemblies 26 to initiate forward flight,as illustrated in FIG. 22B. The next step involves maintaining thethrust vector angles and increasing the pitch down attitude of aircraft10 until the thrust vectors are substantially horizontal, as illustratedin FIG. 22C. Optionally, collective tilting of the aerosurfaces 26 k maybe use such that air blowing thereon generates a pitch down moment foraircraft 10 to urge aircraft 10 in the pitch down direction, asillustrated in FIG. 22C. This is followed by collectively reducing thethrust vector angles and increasing the pitch down attitude whilemaintaining the thrust vectors substantially horizontal until the wingsare also substantially horizontal, as seen in the progression of FIGS.22C-22E. In the high thrust to weight configuration of aircraft 10, thecommand authority provided by collective thrust vectoring may providethe most efficient response when transitioning from VTOL orientation tobiplane orientation is desired.

The foregoing description of embodiments of the disclosure has beenpresented for purposes of illustration and description. It is notintended to be exhaustive or to limit the disclosure to the precise formdisclosed, and modifications and variations are possible in light of theabove teachings or may be acquired from practice of the disclosure. Theembodiments were chosen and described in order to explain the principalsof the disclosure and its practical application to enable one skilled inthe art to utilize the disclosure in various embodiments and withvarious modifications as are suited to the particular use contemplated.Other substitutions, modifications, changes and omissions may be made inthe design, operating conditions and arrangement of the embodimentswithout departing from the scope of the present disclosure. Suchmodifications and combinations of the illustrative embodiments as wellas other embodiments will be apparent to persons skilled in the art uponreference to the description. It is, therefore, intended that theappended claims encompass any such modifications or embodiments.

What is claimed is:
 1. An aircraft operable to transition betweenthrust-borne lift in a VTOL orientation and wing-borne lift in a biplaneorientation, the aircraft comprising: an airframe having first andsecond wings with first and second pylons extending therebetween, thefirst and second wings each having first and second outboard nacellestations; a two-dimensional distributed thrust array attached to theairframe, the thrust array including a plurality of outboard propulsionassemblies coupled to the first and second outboard nacelle stations ofthe first and second wings, the thrust array operable to provide thrustfor the aircraft; and a flight control system coupled to the airframeand operable to independently control a rotor speed and a thrust vectorof each of the propulsion assemblies; wherein the flight control systemis configured to: select, based on whether the aircraft is in a lowthrust to weight configuration or a high thrust to weight configuration,a transition procedure for transitioning the aircraft from the VTOLorientation to the biplane orientation; and implement the selectedtransition procedure to cause the aircraft to transition from the VTOLorientation to the biplane orientation; wherein, in the low thrust toweight configuration, the selected transition procedure comprisesestablishing a pitch down flight attitude while engaging in collectivethrust vectoring of the outboard propulsion assemblies to maintain hoverstability followed by collectively reducing the thrust vector angles toinitiate forward flight; and wherein, in the high thrust to weightconfiguration, the selected transition procedure comprises maintaining alevel flight attitude while collectively increasing the thrust vectorangles of the outboard propulsion assemblies to initiate forward flight.2. The aircraft as recited in claim 1 wherein the outboard propulsionassemblies further comprise unidirectional thrust vectoring propulsionassemblies.
 3. The aircraft as recited in claim 1 wherein the outboardpropulsion assemblies further comprise omnidirectional thrust vectoringpropulsion assemblies.
 4. The aircraft as recited in claim 1 wherein thelow thrust to weight configuration further comprises a thrust to weightratio of the aircraft below a predetermined threshold.
 5. The aircraftas recited in claim 4 wherein the predetermined threshold is about 1.4.6. The aircraft as recited in claim 1 wherein the low thrust to weightconfiguration further comprises a thrust to weight ratio of the aircraftbetween about 1.1 and about 1.4.
 7. The aircraft as recited in claim 1wherein the high thrust to weight configuration further comprises athrust to weight ratio of the aircraft above a predetermined threshold.8. The aircraft as recited in claim 7 wherein the predeterminedthreshold is about 1.7.
 9. The aircraft as recited in claim 1 whereinthe first and second wings each have first and second inboard nacellestations; and wherein the thrust array further includes a plurality ofinboard propulsion assemblies coupled to the first and second inboardnacelle stations of the first and second wings.
 10. The aircraft asrecited in claim 9 wherein the outboard propulsion assemblies areomnidirectional thrust vectoring propulsion assemblies and the inboardpropulsion assemblies are non thrust vectoring propulsion assemblies.11. The aircraft as recited in claim 9 wherein the outboard propulsionassemblies are longitudinal thrust vectoring propulsion assemblies andthe inboard propulsion assemblies are lateral thrust vectoringpropulsion assemblies.
 12. The aircraft as recited in claim 9 whereinthe first and second pylons each have an inboard nacelle station; andwherein the thrust array further includes an inboard propulsion assemblycoupled to each of the inboard nacelle stations of the first and secondpylons.
 13. The aircraft as recited in claim 12 wherein the outboardpropulsion assemblies are omnidirectional thrust vectoring propulsionassemblies and the inboard propulsion assemblies are non thrustvectoring propulsion assemblies.
 14. The aircraft as recited in claim 1wherein the pitch down flight attitude while engaging in collectivethrust vectoring of the outboard propulsion assemblies to maintain hoverstability further comprises a pitch down flight attitude of betweenabout 10 degrees and about 20 degrees.
 15. The aircraft as recited inclaim 1 wherein the pitch down flight attitude while engaging incollective thrust vectoring of the outboard propulsion assemblies tomaintain hover stability further comprises a pitch down flight attitudeof between about 20 degrees and about 30 degrees.
 16. The aircraft asrecited in claim 1 wherein, in the low thrust to weight configuration,the selected transition procedure further comprises collectivelyreducing in the thrust vector angles and increasing the pitch downattitude until the thrust vectors are substantially horizontal and thewings are substantially horizontal.
 17. The aircraft as recited in claim1 wherein, in the high thrust to weight configuration, the selectedtransition procedure further comprises maintaining the thrust vectorangles and increasing the pitch down attitude until the thrust vectorsare substantially horizontal.
 18. The aircraft as recited in claim 17wherein, in the high thrust to weight configuration, the selectedtransition procedure further comprises collectively reducing thrustvector angles and increasing the pitch down attitude while maintainingthe thrust vectors substantially horizontal until the wings aresubstantially horizontal.
 19. The aircraft as recited in claim 1 whereineach of the propulsion assemblies furthest comprises an aerosurface andwherein, in the low thrust to weight configuration, the selectedtransition procedure further comprises collectively tilting theaerosurfaces to create a pitch down moment on the aircraft.
 20. Anaircraft operable to transition between thrust-borne lift in a VTOLorientation and wing-borne lift in a biplane orientation, the aircraftcomprising: an airframe having first and second wings with first andsecond pylons extending therebetween, the first and second wings eachhaving first and second outboard nacelle stations; a two-dimensionaldistributed thrust array attached to the airframe, the thrust arrayincluding a plurality of outboard propulsion assemblies coupled to thefirst and second outboard nacelle stations of the first and secondwings, the thrust array operable to provide thrust for the aircraft; anda flight control system coupled to the airframe and operable toindependently control a rotor speed and a thrust vector of each of thepropulsion assemblies; wherein the flight control system is configuredto: select, based on whether the aircraft is in a low thrust to weightconfiguration or a high thrust to weight configuration, a transitionprocedure for transitioning the aircraft from the VTOL orientation tothe biplane orientation; and implement the selected transition procedureto cause the aircraft to transition from the VTOL orientation to thebiplane orientation; wherein, in the low thrust to weight configuration,the selected transition procedure comprises establishing a pitch downflight attitude while engaging in collective thrust vectoring of theoutboard propulsion assemblies to maintain hover stability followed bycollectively reducing the thrust vector angles to initiate forwardflight followed by further collective reduction in the thrust vectorangles and increasing the pitch down attitude until the thrust vectorsand the wings are substantially horizontal; and wherein, in the highthrust to weight configuration, the selected transition procedurecomprises maintaining a level flight attitude while collectivelyincreasing the thrust vector angles of the outboard propulsionassemblies to initiate forward flight followed by maintaining the thrustvector angles and increasing the pitch down attitude until the thrustvectors are substantially horizontal followed by collectively reducingthrust vector angles and increasing the pitch down attitude whilemaintaining the thrust vectors substantially horizontal until the wingsare substantially horizontal.